Started to implement SmartMix support.

Added an option to the settings page.
Added plugin registration.
Added the SmartMix Perl module.
First prototype implementation of SmartMix support

Implemented SmartMix::resolveUrl().
Fixed some Perl::Critic errors.
Fix Perl::Critic error
Implemented SmartMix support for All Access and My Music

Do not use a GoogleMusic plugin option to enable SmartMix. This
is handled by SmartMix itself.
Only search for 5 All Access tracks. Do not search for Albums and
Artists, just for Tracks.
If nothing was found through All Access try My Music.
Merge branch 'v0.3' into feature/SmartMix
Separated My Music and All Access SmartMix support for issue #39
Merge branch 'v0.3' into feature/SmartMix
Version bump.