Emagging Ripleys

You may now emag the Ripley mech to allow guns to be mounted on it. It
does, however, leave an obvious-as-fuck bold red message in the mech's
desc. This will -only- work for the Ripley mech, god help us all if an
Odysseus ever got weapons.
Merge pull request #329 from SamCroswell/master

Emagging Ripleys