controller: remove message version check

This is unnecessary now that we parse incoming messages using the PyLoxi parser
for the message's version.
Merge into master from pull request #101:
update pyloxi to floodlight/loxigen-artifacts@f88f03f18563b2f1929ad5c253... (https://github.com/floodlight/oftest/pull/101)
update pyloxi to floodlight/loxigen-artifacts@148e1f6c2c0be1e6de04b4a0aa3649558b9a235a

Pulls in the bsn_arp_idle extension.
Merge into master from pull request #100:
controller: remove message version check (https://github.com/floodlight/oftest/pull/100)
controller: accept class in the poll exp_msg parameter

This allows us to poll for e.g. ofp.message.bsn_arp_idle instead of
ofp.OFPT_EXPERIMENTER.

The integer type argument is still supported.

Polling for any message is now deprecated.
controller: remove redundant log
controller: include repr(exp_msg) in exception
controller: clean up poll loop
Merge into master from pull request #102:
Support polling for specific message classes (https://github.com/floodlight/oftest/pull/102)
controller: fix string formatting in exception message
Merge into master from pull request #103:
controller: fix string formatting in exception message (https://github.com/floodlight/oftest/pull/103)
removing assertion on capability and logging fix
updating doc
Merge into master from pull request #104:
Verify capability (https://github.com/floodlight/oftest/pull/104)
update pyloxi to floodlight/loxigen-artifacts@0b4fb635bf2c6839a667f01fcc5afb9cc7da3815