docs: mopidy-convert-config usage
docs: Fix typos
scanner: Remove GStreamer options support
docs: serial no longer needs to be mocked
docs: Fix duplicate links
docs: Remove Debian 6 on Raspberry Pi instructions

Debian 7/wheezy is due for release in a couple of weeks.
docs: Remove speculations about sound quality on Raspi
docs: Remove indications of non-specific issues
path: Handle XDG paths as bytes, not unicode
config/ext: Accept unicode defaults
config: Remove ExtensionConfigSchema
path: Only accept bytes as paths
path: Ensure mopidy.__main__ uses bytes for paths
config/path: Pass in expanded value in expanded path type
path: Disallow unknown substitutions in expand_path
local: Do not create missing media/playlists dir
docs: Update copyrights to include 2013
docs: AUR package installs from master
docs: Change wording for proxy config values
docs: Remove config API inheritance diagrams