Fix bug in riak_core_util:rpc_every_member_ann

The utility fun rpc_every_member_ann, uses by several status/console
commands, was written assuming rpc:multicall returned results in the
same order as the provided node list. This is an invalid assumption.
This commit fixes rpc_every_member_ann as well as adds several
additional utility functions to riak_core_util: pmap, multi_rpc,
multi_rpc_ann, and multicall_ann.
Merge pull request #265 from basho/jdb-ordered-rpc