rename airbrake.py to notifier.py
add utils module

first use is for extracting the complete last line
of an exception stack frame
fill out __init__
provide getLogger shortcut

if the AirbrakeHandler can be automatically created
from environment variables
    AIRBRAKE_API_KEY, AIRBRAKE_PROJECT_ID, and AIRBRAKE_ENVIRONMENT

you can use

    import airbrake
    logger = airbrake.getLogger()

and the logger object will include the configured AB Handler
automatically use environment variables

airbrake.io project id:
    $AIRBRAKE_PROJECT_ID

airbrake.io api key:
    $AIRBRAKE_API_KEY

current airbrake environment name
    $AIRBRAKE_ENVIRONMENT
various improvements in logic and usability

slightly changes some method signatures, primarily
airbrake.notifier.log and
the airbrake.notifier.Error class

If used as a logging handler, the useful values from
the LogRecord will now be set as parameters in the JSON
on error reporting
update setup.py
add a few unittests