s/java_package_manager/ansible_pkg_mgr/g

Ansible provides a fact "ansible_pkg_mgr". Use that in favor of
creating a variable ourselfes.
Allow pre-install configuration of gitolite.rc

This allows to initialize gitolite with site specific custom
configuration which helps not to deal with gitolite init.
Merge branch 'gitoliterc' into next
ansible-gitolite 0.5.0