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).