config: Start adding basic validators + tests for new config values.
config: Add ConfigValue base class and tests.
config: Add String config value and tests.
config: Improve validate error messages and fix handling of non-string choices.
config: Add Integer ConfigValue and tests.
config: Add Boolean ConfigValue and tests.
config: Add List ConfigValue and tests.
config: Add LogLevel ConfigValue and tests.
config: Switch to non context manager version of assertRaises
config: Add Hostname and Port ConfigValues and tests.
spotify: Define extension
local: Define extension
stream: Define extension
mpd: Define extension
mpris: Define extension
http: Define extension
lastfm: Define extension
Add ext prefix to config sections
Merge pull request #376 from trefis/develop

Adds "Starred" playlist to the playlists catalog
spotify: Fix style