[JENKINS-16914] document requirement for remote.remoteName.url
git-fetch JGit implementation
include test to cover tag update
log Git client implementation being used
implement setRemoteURL with JGit
option to select jgit implementation when creating GitClient
[FIXED JENKINS-12188]
[maven-release-plugin] prepare release git-client-1.0.3
[maven-release-plugin] prepare for next development iteration