add/use IDENTIFY command for compatibility with nsqd 0.2.16
Merge pull request #5 from mreiferson/identify_5

add/use IDENTIFY
bump to 0.3.1; add ChangeLog
add TOUCH command; message object now has instance methods for FIN/REQ/TOUCH
give Message a respond attr to communicate back through Reader
change to all constants, some time_ms stuff
make task lookup a method
pass message to _get_method_callback
make constants available
fix indentation, rearrange arg order for invocation as method
== -> is
show invalid response
translate to constants in deprecated finisher