[JENKINS-21952] Resolve tags with slashes

If no revisions are found, try to use the branch as explicit reference.
This could be a tag rel/my-tags or any other explicit reference like a
gerrit changeset (refs/changes/xx/yy/z).
Trivial improvement

removed unncessary addAll call.
Fixed help and added docu for namespaced branches

See git-client-plugin Pull Request
https://github.com/jenkinsci/git-client-plugin/pull/120
Reverted wrong change regarding "any branch"
Switched to new git-client 1.6.4 containing namespace fix
Merge pull request #207 from alexanderlink/namespace-branch-help

Fixed help and added docu for namespaced branches
Fix to allow "remotes/origin/" in branch spec

https://issues.jenkins-ci.org/browse/JENKINS-20767
See comment:
https://issues.jenkins-ci.org/browse/JENKINS-20767?focusedCommentId=196575&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-196575
Added test for remotes/origin/ branches
Merge pull request #209 from alexanderlink/buildChooserFix

Fix to allow "remotes/origin/" in branch spec
Merge pull request #205 from pauxus/21952-tags-with-slashes

[JENKINS-21952] Resolve tags with slashes
Add test that a tag with a slash can be a branch spec
repository browser URL not saved
Test JENKINS-22604 - browser setting is lost when config is saved
Add Apache httpcomponents as a test time dependency

The new config round trip test fails without that test time dependency.
Merge pull request #211 from MarkEWaite/master-add-browser-url-round-trip-test

Test [Fixed JENKINS-22604] - browser setting is lost when config is saved
Merge remote-tracking branch 'upstream/master'