Fix racecondition triggered KeyError in our DebugThread.
Update authors list
spotify: Remove gst import from spotify.playback module
Revert "spotify: Remove gst import from spotify.playback module"

This reverts commit 0459f037a4e51886ccfbbdb59e7b70cea60e5f03.
spotify: Remove gst import from spotify.playback module
Revert "spotify: Remove gst import from spotify.playback module"

This reverts commit b4028e9c577c03277cfc39b24b070fd4868a3847.
docs: Add woutervanwijk's web client
settings: Update settings validator to support empty iterables.
stream backend: Add StreamBackend, fixes #151

Adds a basic streaming backend simply handles streaming audio and nothing else.
I.e. no metadata beyond the URI we where given. #270 still needs to be solved
for actual metadata to make sense in this backend.
core: Update BaseLibraryProvider to not require refresh, search or find_exact.

These methods may now return None, and the core code has been updated to filter
out missing SearchResults.
core: Update tests with cases for filtering out None results.
audio: Move supported URI checking to mopidy.audio.utils

In order to avoid gstreamer imports leaking into more of our code I'm moving
this to a new utils class in audio.
scanner: Support symlinks
Merge pull request #295 from adamcik/feature/streaming-backend

Add basic streaming backend support.
Fix flake8 warnings
docs: Document new backend
docs: Add stream backend to changelog
docs: Add period for consistency
docs: Add more periods for consistency
Fix Python 2.6.0/2.6.1 support (fixes #302)