Remove duplication of methods in AvatarLoader, minor cleanup.
Make field immutable.
Convert private field to local variable.

Closes #386
no need for javadoc on private methods
caching avatars using urls, not userId

Closes #349
storing avatars in a separate folder for user

All avatars for a user are stored in a separate folder with the
user id as the name. All files in that folder are deleted before
writing a new one if the avatar doesn't already exist in that folder.
This should solve the problem with the old avatars when
avatar url is changed.
Remove unused parameters in CommitDiffListFragment

Remove unused parameter from private method,
reduce scope of local variables.
Closes #387
added a posibility to open commits compare screen for pull-requests. issues screen now has 'commits' button
commit icon near to 'commits' field
moved 'commits' label below the description
Use ViewFinder to set text on TextViews
Merge pull request #347 from atermenji/pr_commits

Commits list for pull-requests
Fix typo in method name.

Closes #391
Add contributors screen
Open UserViewActivity on click to contributors list item
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