Add a few assertions, use explicitly typed collection in test
Use explicitly typed list in JGitAPIImpl
Removed unused imports
ObjectID's should be same, not Ref's - Fix broken unit test assertion
Update to Jenkins dependency to 1.509.3 for credentials test
Add an invalid credential, use it
Add trivial authentication test cases for JGit and CliGit

Confirm that invalid authentication does not break clone from
repositories which do not require authentication.
Merge branch 'proto-add-credentials-attempt-01' into master-work

Conflicts:
	src/test/java/org/jenkinsci/plugins/gitclient/GitAPITestCase.java