fixes #137 - Better support for non-hostname certnames

This patch introduce a new setting :use_uuid_for_certificates which
defaults to false.

users who wish to deploy their hosts using a random unique id, should
enable that setting, and use the certname directive in their puppet.conf...

Changes to dashboard statistics. Fixes #1617

Compute Resource menu was shown only if libvirt bindings were installed

fixes #1610 - exdception in the ui when editing a deleted vm.

fixes #1609 - REST API calls /hosts/:id/puppetclasses fails for hosts with same class assigned directly and through host group

fixes #1606 - foreman returns to main screen after session expiry

refs #1503, ensures that puppet proxy is not required if you are not provisioning

UI fixed error in provisioning template, edit page.

fixes #1603 - Login Screen improvments

UI - more explicit button description for the add child node.