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.

Imported some of the GPLv3'd changes from RhodeCode v2.2.5.

This imports changes between changesets 21af6c4eab3d and 6177597791c2 in
RhodeCode's original repository, including only changes to Python files and HTML.

RhodeCode clearly licensed its changes to these files under GPLv3
in their /LICENSE file, which states the following:
The Python code and integrated HTML are licensed under the GPLv3 license.

(See:
https://code.rhodecode.com/rhodecode/files/v2.2.5/LICENSE
or
http://web.archive.org/web/20140512193334/https://code.rhodecode.com/rhodecode/files/f3b123159901f15426d18e3dc395e8369f70ebe0/LICENSE
for an online copy of that LICENSE file)

Conservancy reviewed these changes and confirmed that they can be licensed as
a whole to the Kallithea project under GPLv3-only.

While some of the contents committed herein are clearly licensed
GPLv3-or-later, on the whole we must assume the are GPLv3-only, since the
statement above from RhodeCode indicates that they intend GPLv3-only as their
license, per GPLv3§14 and other relevant sections of GPLv3.

Implemented simple gist functionality ref #530.

- creation of public/private gists with given lifetime
- rhodecode-gist CLI for quick gist creation

more usage of fixture tools
in tests

compare/pullrequest: introduce merge parameter

This is more correct and flexible than the old way of looking on same/different
repo.

compare: cleanup of as_form handling

as_form is only used when loaded 'partial' from pullrequest.html. Including it
in the 'Detailed compare view' url did thus not do any harm.

as_form is never used in pullrequest_show.html or compare_diff.html and it is
thus never used together with swap_url ... which is why the wrong
'as_form=None' or 'as_form=False' in urls didn't do any harm.

fixed pull-requests with cherry picking changesets
- fixed tests for them

compare: swap org and other when they refer to different repos, ie are pull request style

Pull requests will have a different from/to description - but in a consistent
and slightly better way that can be improved later.

A pull request diff is empathic: "How will this look for the peer I'm proposing to" style.

compare: rename optional compare_url parameter repo to other_repo

At the same time it is placed before other_ref_type and other_ref. Just to keep
a logical flow and (a new) consistency that will help the next refactoring.

Basic implementation of cherry picking changesets
for pull request, ref #575

Multiple changes for compare system
- count number of changed lines and files
- add combined compare button into the old per changeset compare
- fixed some logic for remote & bundle compare system
- added few tests for git compare

#590 Add GET flag that controls the way the diff are generated, for pull requests we want to use non-bundle based diffs,
That are far better for doing code reviews. The /compare url still uses bundle compare for full comparision including the incoming changesets.
- Fixed tests

Permissions on group can be set in recursive mode setting defined permission to all children
- more explicit permissions
- fixes for empty values in permission form

fixes #550 mercurial repositories comparision failed when origin repo had
additional not-common changesets + added regresion test for this

Bumped mercurial version to 2.3
- fixed issues with compare of two remote repos at particular revisions
- added tests for cases when mercurial update broke code and tests didn't catch this
- removed obsolete EmptyChangeset from the rhodecode code

Added basic models for saving open pull requests
- added pull-request models
- added pull-requests notifications into inbox