fix for BUG-956 - deadlock by rpc invocation

- fixed future chaining
- added rpcPool for asynchronous processing

Change-Id: I19c9b94e383f3e3f5bfff179a966b1950a942821
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>
Signed-off-by: Michal Rehak <mirehak@cisco.com>