"update_plugins" should try to install all the plugins in lib/earth_plugins.
- If they are all up-to-date do nothing (i.e. if the versions of the plugins in the db match the ones in the directory)
- If they need to be installed - check that they have been signed - then install them.
- If the plugin hasn't been signed - check that a certificate and private key exists - then sign the plugin
- If the certificate and private key don't exist create them and tell the user to keep the private key very safe
By the way, can the public key easily be regenerated from the private key?
This should make it all very easy for the user. :-)
