ui: hide episode detail views if information is null

e.g. if there is no first aired date for an episode in the database
then hide the view instead of saying the episode was first aired in
1970.
use support library activities, fragments, and loaders

doesn't affect our min sdk version as we still use action bar and
recent themes/styles
add ActionBarSherlock

Add as a git submodule.

Have made a local commit to the submodule though:
Overwrite the support library jar that it bundles in its libs
folder with the same one that we bundle in our libs folder. Also
change its project.properties to build against the same sdk version
as us.

Add a library reference to it in project.properties.