Added online IOPs measurement.

Added support for different servers serving different clients.
1GB distributed across 8 server processes does better than 1 GB in
one server process.
New shell scripts..
Added support for multiple regions at the server and multiple receive buffers at the client.

1. The server registers [NUM_SERVER_EXTENTS] memory regions.
2. The client registers [READS_PER_ITER] memory regions.
3. In each RDMA read iteration, the client chooses a server region at random
and reads from it.