fix the server to parse all available data in TCP buffer
fix the server to parse all available data in TCP buffer

- there might be situations where more than a single RPC call has
  been received, so make sure we parse all data.
- fix the shifting mechanism of un-parsed data in the existing
  buffer.

Change-Id: I1f560673aaaca043af06376db58b3a3efc7348c6

airtame/jsonrpc-c