make rpc faster in python, using ZMQIOLoop to poll message in future.wait function
minor changes, fix the bug in remove_handler
add rpc test
change all the loop to event_loop
a bunch of changes according to code review
close serversocket when the loop ends. remove setupclass and teardownclass method in perf test
use poller inside future instead of loop to control the timeout. a bunch of other changes according the code review
Merge pull request #102 from EasonLiao/rpc_optimize

make rpc faster in python,  using tornado.ioloop to poll message in future.wait function.