AUXPOW/Merged-mining support

[Cminor-pools]

Hi guys, cant merge mine, missing rpc aux calls, no getauxblock or createauxblock/submitauxblock

[DevElCuy]

@Cminor-pools, RPC calls createauxblock and submitauxblock are now available in latest code (master branch). Please build again and let us know how it works your side.