fix heartbeat interval to send along in milliseconds
connection attributes not client
add new versions of tornado; drop 1.2.1 support (not pip installable)
Merge pull request #64 from jehiah/tornado_support_64

torando supported versions: add 3.1, 3.2 drop 1.2.1
Merge pull request #63 from jehiah/heartbeat_unit_63

heartbeat interval: send as milliseconds