cli: convert 'gearbox cleanup-repos' into 'kallithea-cli repo-purge-deleted'

Some changes to user-facing text are done.

gearbox: replace paster with something TurboGears2-ish that still works with the Pylons stack

This is a step towards moving away from the Pylons stack to TurboGears2, but
still independent of it.


Some notes from the porting - it could perhaps be the missing(?) documentation
for migrating from paster to gearbox:

Note: 'gearbox' without parameters will crash - specify '-h' to get started
testing.

Replace paster
summary = 'yada yada'
with the first line of the docstring of the Command class ... or override
get_description.

Note: All newlines in the docstring will be collapsed and mangle the long help
text.

Grouping of commands is not possible. Standard commands (for development) can't
be customized under the same name or hidden. (Like for paster, the conceptual
model also assumes that the sub-command naming is namespaced so commands from
other packages won't conflict.)

The usage help is fully automated from the declared options.

For all deprecated Commands, replace paster
hidden = True
with gearbox
deprecated = True

Note: config_file, takes_config_file, min_args and max_args are not available /
relevant.

The gearbox parser is customized by overriding get_parser - there is nothing
like paster update_parser.

Gearbox is using argparse instead of optparse ... but argparse add_argument is
mostly backwards compatible with optparse add_option.

Instead of overriding command or run as in paster, override take_action in
gearbox. The parsed arguments are passed to take_action, not available on the
command instance.

Paster BadCommand is not available and must be handled manually, terminating
with sys.exit(1).

There is no standard make-config command in gearbox.

Paster appinstall has been replaced by the somewhat different setup_app module
in gearbox. There is still no clean way to pass parameters to SetupAppCommand
and it relies on websetup and other apparently unnecessary complexity. Instead,
implement setup-db from scratch.


Minor change by Thomas De Schampheleire: add gearbox logging configuration.
Because we use logging.config.fileConfig(.inifile) during gearbox command
execution, the logging settings need to be correct and contain a block for
gearbox logging itself. Otherwise, errors in command processing are not even
visible and the command exits silently.

cleanup: use example.com for tests and examples

example.com is explicitly reserved for this purpose. Using that means
we won't accidentally hammer a real server or real email address if an
example value escapes into the wild, e.g. in an automated test.

The domain "kallithea.example.com" has been used throughout to refer to the
example Kallithea server.

docs: consistent spacing around headings

Start out with 2 empty lines before/after for top level, decrease for deeper
levels.

docs: cleanup of casing, markup and spacing of headings

Mostly stuff found and fixed by Søren, extracted here to separate things.

Other uses of title casing might be debatable, but here it was just a few
documentation headings that clearly were inconsistent with the majority.

spelling: use "email" consistently

The common English spelling is "email", not "e-mail" (and was indeed
also the most common, but not only, variant in the Kallithea UI).

http://grammarist.com/style/e-mail-email/

docs/usage: fix section 'trending source files'

The source code reference for the 'trending source files' dictionary was no
longer correct, so update it.
Additionally, some small rewording.

docs/usage: rework and rename section 'Visual settings in admin pannel'

- remove trivial items that are already explained on the settings page
itself
- rename section to reflect this new scope
- general rewording

docs: rework stuff

The existing docs were far from how we wanted it to be. There was so much to do
and it is not feasible to do that cleanup it in clean patches.

Instead, I took a sweep through the docs and changed what I thought could
benefit from a change: structure, examples, advices, language, markup, content,
etc.

First step in two-part process to rename directories to kallithea.
This first step is to change all references in the files where they refer
to the old directory name.

changelog / compare: adjust titles

Clarify what shows changesets and what more see changesets as revisions that
specify snapshots that are compared.

Fixed validators for remote repos
- use proper httppeer repo for mercurial 2.3
- validate git repos for remote auth
- docs updates

added initial rc-extension module

- possible to store additional mappings for stats
- possible to overwrite and add to whoosh index extensions
issue #322
- post create repo hook callback
- post push/pull hooks callback