Rename createUserAccount messages to registerNym.
Rename the rest of createUserAccount to registerNym.

Client API, enums, etc.
Merge pull request #415 from benma/registerNym

Rename createUserAccount to registerNym.
rewrite OTData, new ot_data_t typedef
update OTCrypto to make use of new OTData
update OTASCIIArmor to make use of new OTData
update OTEnvelope to make use of new OTData
update OTSymmetricKey to make use of new OTData
headers updated to make use of new OTData
updated OTAsymmetricKey to make use of new OTData
updated ot core to make use of new OTData
udpated remaining ot to make use of new OTData
gcc fixup for OTLog OT_HANDLE_SIGNAL