move and rework SendMoney to rpcwallet

- as SendMoney is ONLY used in rpcwallet move it there
- also rework the function to not log errors but use throw JSCONRPCError
- removes a check for IsLocked() that is done in sendtoaddress and
  sendfrom RPC calls already
- remove translations in SendMoney (never used in the GUI)
- fixes #3007

Intended for discussion, also I was thinking about extending our wallet error codes, as most errors in ``SendMoney`` use the generic ``RPC_WALLET_ERROR``.