typedef std::vector<unsigned char>.

Introduce a typedef for std::vector<unsigned char> to simplify life in
the future.
Implement name_pending RPC call.

Add a new RPC call "name_pending" that lists all pending name operations
in the memory pool together with some decoded information (operation
performed and value the name is set to).
Merge pull request #27 from domob1812/name-pending

RPC call for pending names