Fix git command in deploy.sh

Because jenkins works on a detached HEAD, the git command that we were using to try to push the commits back up to github was invalid.  This commit changes the script to use an environment variable (populated by a Jenkins build parameter) to determine the correct branch name.

jenkins/deploy.sh

@@ -11,6 +11,6 @@ echo "Tests passed!"
 lein release
 echo "Release plugin successful, pushing changes to git"
 
-git push origin --tags `git rev-parse --abbrev-ref HEAD`
+git push origin --tags HEAD:$TRAPPERKEEPER_BRANCH
 
 echo "git push successful."