[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
Use BuildChooserContext environment in InverseBuildChooser

Fixes an issue introduced by 4fc7f4447c990082e8322c42ebafd1f33a2e60aa.

When polling git for changes, context.getBuild() returns null, manifesting in an NPE from  InverseBuildChooser.getCandidateRevisions() when polling a git repo and using an Inverse branch choosing strategy.

This was fixed for DefaultBuildChooser in 68331baf78649becac426b9362534faff08cf618--BuildChooserContext now includes the appropriate environment, so there is no longer any need to call context.getBuild().getEnvironment() as demonstrated in [DefaultBuildChooser.java](https://github.com/jenkinsci/git-plugin/commit/68331baf78649becac426b9362534faff08cf618#diff-59b21aee0282fdafd62036844373a19cL190).
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
Added tests of pull request #93: Fix include/exclude filters to consider every new commit
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'
Enable use of trackingSubmodules

trackingSubmodules were introduced in v1.8.2 of GIT as a way to always
track the tip of the branch you are interested in for a submodule.  This
is turned on via the --remote switch to 'git submodule update'.  This
allows you to always stay up to date (--remote) or to just use the
specific SHA-1 you last downloaded (no --remote).

So, we now surface this new feature in the UI.  It requires corresponding
changes to the git-client-plugin (Pull request 122) for this to compile.
Use SubmoduleUpdateCommand

The SubmoduleUpdateCommand pattern allows for easier understanding of what each
of the parameters means.