Docs/usage on scheduler/worker need to be updated

A couple things:

1. The admin docs (doc/admin/installation.rst) says to run ./bin/scheduler -vv and ./bin/worker -vv to start a single scheduler/worker node. This doesn't work anymore and needs to be updated.
2. Running ./bin/scheduler --help gives the following message after the usage/options sections:

Examples:

  To start the scheduling process do the following:

    $ scheduler

  You can pass the ``-v`` flag to start the scheduler with the logging level
  set to ``INFO`` or ``-vv`` to set it to ``DEBUG``. By default, the logging
  level is set to ``WARNING`` if no ``-v`` flag is passed.

This isn't correct either.

Running ./bin/scheduler gives the following error:

Traceback (most recent call last):
  File "./bin/scheduler", line 26, in <module>
    sys.exit(beat.web.scripts.scheduler.main())
  File "/home/jae/work/beat.web/beat/web/scripts/scheduler.py", line 219, in main
    int(arguments['--port']),
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

I tried providing a valid value to the --port argument: ./bin/scheduler --port=9101, but it gave me a ZMQ error:

Traceback (most recent call last):
  File "./bin/scheduler", line 26, in <module>
    sys.exit(beat.web.scripts.scheduler.main())
  File "/home/jae/work/beat.web/beat/web/scripts/scheduler.py", line 222, in main
    onWorkerGone = onWorkerGone,
  File "/home/jae/miniconda3/envs/beat-web/lib/python3.6/site-packages/beat/core/worker.py", line 99, in __init__                                                            
    self.socket.bind(self.address)
  File "zmq/backend/cython/socket.pyx", line 547, in zmq.backend.cython.socket.Socket.bind                                                                                   
  File "zmq/backend/cython/checkrc.pxd", line 25, in zmq.backend.cython.checkrc._check_rc                                                                                    
zmq.error.ZMQError: No such device

Trying to start a worker node via ./bin/worker gives the following message:

Usage:
  worker [-v ... | --verbose ...] [ --name=<name>] [--prefix=<path>]
           [--cache=<path>] [--docker] [--docker-network=<name>]
           [--port-range=<range>] <scheduler_address>
  worker (--help | -h)
  worker (--version | -V)

I did all this while ./bin/django runserver was running in a different window.

This is a blocker on some of my work as I need to run experiments successfully to create reports to work on the report-related issues.