Merge pull request #336 from atermenji/contributors

Add contributors screen
Fix NPE when opening PR issue from news screen

ViewFinder was not initialized by subview, so direct casting needed.
Remove unused menu file
Update http-request to the latest 5.4 version
[i18n] update german translation

Closes #392
Move search repo classes to new ui.search package
Add skeleton classes for SearchActivity and Search Fragments
Create tab pager for repos/users search fragments
Remove unneeded files
Fix SearchActivityTest
Implement search for a particular user
Implement requery from SearchActivity
Add SearchUser model class
Implementation of SearchUserService

SearchUserService is an extension to UserService
with methods for users search using Search API
UI for searching users

Add SearchUserListAdapter, support for SearchUser class in
AvatarLoader
Rename searchable meta-data