Avoid unnecessary errors in the single host case.

The multi-master replication/topology patches allowed a topology of one
host, however now this topology correctly returns empty.

Sorry, but a single, lonely ipa server can't hold hands with itself :(
Replace old crufty /etc/hosts management with vagrant-hostmanager.

This depends on two patches:

https://github.com/smdahlen/vagrant-hostmanager/pull/109
https://github.com/smdahlen/vagrant-hostmanager/pull/111

If they are not merged shortly, please look for them here:

https://github.com/purpleidea/vagrant-hostmanager