Use constants for string/byte literals
Merge pull request #111 from ijl/constants

Use constants for string/byte literals
Fix attributes defined outside of __init__
user_agent default. pep8 on async module.
Compile regex
Alias duplicate method on SendError
nsq.nsq to nsq.protocol
Merge pull request #114 from ijl/misc_refactor

Misc refactor
update test suite versions
bump 0.6.6-alpha