Block call trial implementation for review. With tests added. Please review

[linearregression]

• A trial implementation of block_call that I left half way in the process. Implementation:
• block_call(Node, M, F, RecvTO)
• block_call(Node, M, F, A, RecvTO
• block_call(Node, M, F, A, RecvTO, SendTO)

Basically the same as Call except not have a worker to handle the call processing. Rpc doc on block_call refers to not creating a separate process to handle the call. Block the RPC server from any other incoming requests until the request has been handled....

• Since there is no worker process and the intention is to block RPC server.
• RecvTO for gen_server:call inside block_call. Call will timeout on request if result does not arrive within timeout.
• SendTO remains as it has nothing to do with call execution but more or less on network etc.
• The CallerPid is sent along with the Actual Request to server. The result from server that comes back to gen_rpc_client returns with the CallerPid.
• Despite some waste, There is no need to keep track of the CallerPid if it is part of the Request and Result payload.
• The gen_rpc_client will gen_server:reply to Caller with the Result.

If this is incorrect or you have better approach, please feel free to rework/junk it as you see fit.

Ref: http://www.erlang.org/doc/man/rpc.html

[linearregression]

Sorry for pushing to get PR's review. It will be nice to get some reviewed?

[linearregression]

Closed. Refer to the cleanup verison. https://github.com/priestjim/gen_rpc/pull/41