Add and subtract some things from the tarball

MANIFEST.in

+prune v2
+prune docsite
+prune ticket_stubs
+prune packaging
+prune test
+prune hacking
 include README.md packaging/rpm/ansible.spec COPYING
 include examples/hosts
 include examples/ansible.cfg
 include lib/ansible/module_utils/powershell.ps1
 recursive-include lib/ansible/modules *
 recursive-include docs *
+recursive-include plugins *
 include Makefile
 include VERSION
 include MANIFEST.in