Add an API to retreive all keys signed by some key
If I set Alice as a trusted introducer, then I might want to find all keys that she has signed. Currently, this is non-trivial, because certifications are associated with the signed keys and not the signer's key. I propose adding an API by extending the HKP API to return this information.
The method might return a key ring with each key that the specified user signed. To limit the amount of data that needs to be transferred these keys could be minimized.