models: Don't allow model deserialization to override methods
models: Model creation with kwarg matching method name should fail
models: Change serialized type marker from '__type__' to '__model__'
Merge branch 'feature/model-serialization' into develop
Merge branch 'develop' into feature/http-frontend
mpd: Test response for bad 'list' requests
mpd: Allow bad 'find' requests
docs: Fix docstring errors
core: Make tracklist.version read-only
core: Expose getters/setters for all properties

This will be useful when exposing the core API over various protocols, e.g.
JSON-RPC.
tests: Rename populate_playlist() to populate_tracklist()
spotify: Require pyspotify 1.9
Merge pull request #248 from Dvad/develop

spotify: Add proxy support
settings: Tweak docstrings
docs: Add Spotify proxy support to changelog
spotify: Only pause on connection error if playing

Spotify has availability issues today, which makes this easy to reproduce and
improve. Before this patch, the following was logged on a Spotify connection
error when not playing:

ERROR    Spotify connection error: Can not connect to Spotify
WARNING  Setting GStreamer state to GST_STATE_PAUSED failed
ERROR    Resource not found. gstplaybin2.c(3824): setup_next_source ():
/GstPlayBin2:playbin20

With this patch, only the first and relevant error message is logged.
spotify: Fix resume which was broken by fix for #227
Merge pull request #251 from jodal/feature/core-getters-and-setters

core: Expose getters/setters for all properties
core: Remove playback.track_at_next
core: Remove playback.track_at_eot