Update pom dependencies to match git plugin - JGit and Jenkins

Updated JGit to 3.2.0

Updated Jenkins to 1.480

Updated two other dependent libraries to their most recent versions.
Update git plugin dependency to 2.0.1 - latest git plugin version
Merge pull request #2 from MarkEWaite/master-JENKINS-21163-startup-fails

[FIXED JENKINS-21163] Update pom dependencies to match git plugin - JGit and Jenkins