mpd: playlist name disambiguation
mpd: fix style issues and type errors introduced in 87ce309
Tests are now OK
mpd: minor style commit
mpd: bugfix in MpdContext.create_unique_name
mpd: added a test to check playlists names uniqueness
mpd: 'private' fields start with an _
Revert "mpd: 'private' fields start with an _"

This reverts commit f2000d6e6df362fa9c07379a483d91cf2b67ce88.

I did not have the code fresh in mind when saying that these should be prefixed
with _. As they are accessed from other classes, they are indeed public, and
should not be prefixed. My bad.
mpd: Fix flake8 warnings
mpd: Start numbering of duplicate playlist names at 2
Merge branch 'develop' into pr/396

Conflicts:
	mopidy/frontends/mpd/dispatcher.py
Merge pull request #396 from trefis/develop
Update changelog