Issue883/add check for different front end

[kchilleri]

This PR adds a database to the client to keep track of the name of the front end where beeflow is started. Every time a beeflow core * command is submitted, we check if the current front end is the same as the one where beeflow was started from. If not, it returns a warning and exits.

[kchilleri]

To Do:

1. Add more error checking.
2. Add testing (I have a test for the database but need a separate one for the rest of the code).

[pagrubel]

I was able to do a "beeflow core start" on a front end different than one that had beeflow running on it. I don't see a check for this in beeflow start command in core.py

[pagrubel]

It looks like there is only a check for the commands beeflow core status and stop
There should also be checks for start , restart, and reset.

It isn't needed for pull-deps or info though

[kchilleri]

@pagrubel I am not adding checks to restart and reset commands because they call the stop function which already contains the check, but I will add one to the start command

[pagrubel]

@pagrubel I am not adding checks to restart and reset commands because they call the stop function which already contains the check, but I will add one to the start command

That makes sense for restart but reset does quite a bit of checking before it does the stop so I think a check there might be warranted

[pagrubel]

This works for reset and start now.