Add stub for waitforblock async call.
Add stub for waitforblock async call.

Add a new "waitforblock" async RPC call, that currently just sleeps for
some time instead of doing actual things.

bankonmecoin/namecoin-legacy,jonasbits/namecoin,cfromknecht/namecoin-legacy,eXcomm/namecoin,rsackler/namecoin,cryptostorm/namecoin,cfromknecht/namecoin-legacy,cryptostorm/namecoin,rsackler/namecoin,Midar/namecoin,Midar/namecoin,eXcomm/namecoin,jonasbits/namecoin,jonasbits/namecoin,namecoin/namecoin,cfromknecht/namecoin-legacy,okTurtles/namecoin,fflo/sixeleven,Midar/namecoin,okTurtles/namecoin,okTurtles/namecoin,Midar/namecoin,namecoin/namecoin-legacy,jonasbits/namecoin,okTurtles/namecoin,Midar/namecoin,namecoin/namecoin-legacy,eXcomm/namecoin,eXcomm/namecoin,namecoin/namecoin,namecoin/namecoin-legacy,fflo/sixeleven,rsackler/namecoin,cryptostorm/namecoin,bankonmecoin/namecoin-legacy,namecoin/namecoin,cryptostorm/namecoin,cfromknecht/namecoin-legacy,cfromknecht/namecoin-legacy,namecoin/namecoin,namecoin/namecoin,rsackler/namecoin,rsackler/namecoin,jonasbits/namecoin,bankonmecoin/namecoin-legacy,okTurtles/namecoin,bankonmecoin/namecoin-legacy,namecoin/namecoin-legacy,fflo/sixeleven,bankonmecoin/namecoin-legacy,eXcomm/namecoin,cryptostorm/namecoin,fflo/sixeleven,namecoin/namecoin-legacy