repository: functions now get gandalf endpoint to return git urls

Relates to #353
provision/docker: starting gandalf test server when needed

Relates to #353
testing: creates simple test handler.
provision/docker: using test handler from testing package.
testing/setup.go: exporting TestHandler fields for tests purpose.
repository: using TestHandler from testing package
provision/juju/provosioner_test: starting gandalf server when needed

Relates to #353
deploy/git_test: starting gandalf test server when needed

Closes #353