Merge pull request #131 from joaopaulovieira/master

Create GetDiff for return diff between commits
go fmt ./...
updated CONTRIBUTORS.
Added handler to return a list of repository tags (Fix #120)
travis: checking format.
Merge pull request #133 from marcelometal/get_tags

Added handler to return a list of repository tags (Fix #120)
travis: getting apt output.
Added zipArchive and tarArchive in the GetForEachRef
Merge pull request #136 from marcelometal/links

Added zipArchive and tarArchive in the GetForEachRef
add GetDiff Handler
fixed merge problem
Merge branch 'master' of github.com:joaopaulovieira/gandalf

Conflicts:
	api/handler.go
	api/handler_test.go
	webserver/main.go