backend/core: Switch to root_directory instead of name
core: Update browse to use uri isntead of path
local: Convert local browsing to uri based system.
mpd: Switch mpd to use path<->uri mapping for browsing
review: Typos and code formating
review: Update browse docstring with respect to URI type
Merge pull request #647 from adamcik/feature/browse-by-uri

Convert browse API to be fully URI based.