* Replaced async keyword with is_async in the Queue class to fix reserved keyword syntax errors in Python 3.7
* Updated tests to use is_async keyword when instantiating Queue objects
* Updated docs to reference is_async keyword for Queue objects
* Updated tox.ini, setup.py and .travis.yml with references to Python 3.7
- run with an empty queue
- schedule one job (which uses get_current_connection and get_current_job) and
run `rqworker`
- schedule a job that itself schedules `access_self` and run `rqworker`
- Make sure the job didn't fail by assuring the failed queue is still empty
afterwards.
- Install this package locally when running in travis.
This actually unifies the behaviour of tox and travis as tox also builds the
package and then installs it into each test environment.
- fix flake8 (as run by tox)