application: Load the css file from resources
Make the application identifier and resource paths consistent
Make the default duration 0:00 instead of 00:00

This makes sure that the duration label won't change size on first
playback.
view: Fix iter error in songs view
view: Define iter_to_clean in songs view

Also, rename from camelCase to lower_case.
player: Fix end of playlist on repeat none
Merge pull request #57 from kyoushuu/master

Various fixes in resources, songs view and playback