1. Added documentation to the README on the possible options to run the
Redis service.
2. Show a relevant message to the user if the application is run with
`--start-redis` and Redis couldn't start.
3. Some LINT/black chores on some files that hadn't been touched in a
while.
- Refactored the logic for executing a request and wrapping the response common to procedures, crons and event hook decorators into platypush.common.exec_wrapper
- Added mock getvalue() method to Logger to prevent PyCharm failures in the tests when sys.stdout is redirected to the Logger object
