Moving git_url into git_info dictionary

This patch is done in anticipation of adding extra
git information like the branch and private keys to
expand on unittest-app and build-app's functionality.

Keeping all the information in one dictionary instead of
as additional kwargs will reduce the need for changes to
solum-worker's API.

Change-Id: I4b15e03b183f3cdcd6f9442288a307cb5ec2792f
Merge "Moving git_url into git_info dictionary"