hub: comment
hub: handle GreenletExit internally
hub: add some more tests
controller: stop catching GreenletExit

no longer necessary after the hub changes.
msgpack rpc helper

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
msgpack-rpc fixes and improvements

- make create_request returns msgid
- fix msgid wrap around
- rename classes
- convenient transport classes for socket-like
- update requirements
- copyright notice, comments, and assertions
msgpack-rpc: unit tests