Add salt's git repo as upstream and fetch tags if using a custom git url
Compare the bootstrapped minion commit SHA with the desired one.
Check the cloned repository commit for the appropriate match

This split's the Jenkins script execution into one additional step.
Prepare the source to match the cloned repository commit, then resume
previous steps.
Merge pull request #11793 from s0undt3ch/2014.1

2014.1 jenkins script improvements