Apollo: Fix list padding

Change-Id: I025600c093e294ddd3bede4c088b16e6842747c7
Apollo: Fix artwork download preference

Use correct preference keys for artwork download

These settings were not being respected because the preference key
was wrong

Change-Id: Id37944f00ebf833abb082dc79c7ccd42b517c5dc
Apollo: Avoid crash when attempting to load many items

Thread pool executor will reject additional tasks when it has
exhausted it's queue space causing Apollo to crash.

Load default artwork if executor is too busy.

Change-Id: I7b7a6c45625882f09eac4abc6270be4612f87ccd
Merge pull request #5 from omnirom/android-4.4

omnirom: