cli: fix argv bug just introduced in 2ce0bc6e85f1

Reported by mjacob.

cli: pass local argv to argparser instead of letting it use the global sys.argv

Fix pylint warning: "fix W0613(unused-argument) in argparser: Unused argument 'argv".

lib: clean up ext_json and how it is used - avoid monkey patching

Note that py3 json.dumps will return ASCII (with all unicode escaped) encoded
as str. But we generally want JSON as bytes (which json.loads also can read),
so also wrap the result with ascii_bytes in many places.

py3: cleanup map usage and avoid py3 ambiguity

Based on 2to3 -f map ... but replace map with something more explicit (unless
born and raised in a lisp world) (but sometimes slightly more verbose).

codingstyle: trivial whitespace fixes

Reported by flake8.

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.

remove vestiges of Python 2.5 support

We only support Python 2.6 and 2.7; hence we do not need to import
with-statement support from __future__.

cleanup: make module self-naming consistent

The self naming is quite pointless ... but at least make it right.

cleanup: avoid some 'except Exception' catching - catch specific exceptions or log it and show what happened

This has a risk of introducing regressions ... but we want to get rid of all
exception muting and make the whole system less fragile and easier to debug.

Correct licensing information in individual files.

The top-level license file is now LICENSE.md.

Also, in various places where there should have been joint copyright holders
listed, a single copyright holder was listed. It does not appear easy to add
a link to a large list of copyright holders in these places, so it simply
refers to the fact that various authors hold copyright.

In future, if an easy method is discovered to link to a list from those
places, we should do so.

Finally, text is added to LICENSE.md to point to where the full list of
copyright holders is, and that Kallithea as a whole is GPLv3'd.