* improved @enforce_ordering to leverage a wait channel to avoid spinlocks
* addressed pyflake issues
* renamed wait channel to __wait__.<reply channel>
* handled potential ChannelFull exception
* updated sessions unit tests
* updated enforce_ordering tests to reflect new approach of leveraging wait channels
* addressed pyflake issues
* more pyflake fixes
* removed close_on_error handling on enforce_ordering since only worked on websockets