Monkeysphere module

This adds a "Monkeysphere" page under System, that will list each registered name service. The user can generate a PGP key for each domain, and the PGP fingerprint will be shown. Then the user can publish the key for any domain to the keyservers. Since publishing can take a long time (seems to take forever if there is no response), it is run as a background task that the user can cancel.

I also made a few changes to the Names module:

1. Replace SERVICES list with a get_services() function.
2. If a domain is not available for a service type, return None instead of (translated) "Not Available".