make MasterKeys() more flexible by allowing different key-names.
make MasterKeys() more flexible by allowing different key-names.

MasterKeys() should be able to handle more than one hardcoded key.
The default is still to just handle master.* files but can also generate
new key-pairs with different names and return the pub-key.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt