Reduce scope of methods.

Closes #384
Change up navigation from RepositoryViewActivity
Navigate to the owner's page instead of the HomeActivity

Closes #316, closes #278
Improve Japanese translation

Closes #385
Add JavaDoc.
Remove delegating methods.
Make field immutable.
Remove duplicate method call.
Make local variables immutable.
Remove redundant local variables.
Remove duplication: Extract private method.
Whitespace formatting.
Convert private field to local variable.