Improve performance when handling large repo's

Compatibilizing with a fresh install of ubuntu 12.04 LTS i386 (virtualized)

Clean up application_helper.rb code

Clean up tab_helper.rb code

Use the faster alternative methods in grit to count tags and branches (which I added). This is much faster in all cases, but especially on large repositories the difference should be obvious.

Dashboard feed

Bash path in post-receive-hook

removing /tmp/gitolite-admin in installation script with sudo

Bugfix/encoding

remove detect_enoding. detect_encoding means force_encoding to the file.data's encoding, not encoding to utf8. will cause encoding problem.

Refactoring and assets cleanup

[ci skip]

[ci skip]

Travis and Ruby 1.9.3