File contents handler working
Support for getting file content and repo archive

Now gandalf supports retrieving file's contents in any ref it is (tag,
branch or commit).

Also added support for getting the archive (.tar, .tar.gz or .zip) for
any repository ref (tag, branch or commit).
Docs for both archive and show
Ops... File missing for tests
Fixing issues with code format and proper format - thanks @andrewsmedina
Merge pull request #110 from heynemann/master

Support for git-archive and git-show