Add "lockToDJ" column in Hosts

[Lovinity]

Add an integer column "lockToDJ" to the hosts model. Allow null.

If not null, the node server should deny any attempts to take a break, play a PSA, play a liner, or otherwise do anything that could interfere with another person's show, unless the specified DJ is on the air (Meta.dj).

Furthermore, when starting a remote broadcast, the request should be denied unless the specified DJ from the form matches the "lockToDJ" dj. Requests to start a live or sports show should always be denied when this option is set. But allow starting sports remote broadcasts (only when scheduled); sports broadcasters may have to use their personal computers to do remote sports broadcasts.

Also, these hosts should not be allowed to send any messages to web visitors if another DJ is live.

Also, these hosts should not be allowed to send any messages to the display sign.

This is so we can begin allowing DJs to do shows remotely by installing DJ Controls on their personal computers.

• [x] Implement model column

• [x] Implement restrictions on controllers

• [x] Implement changes in DJ Controls https://github.com/Lovinity/wwsu-dj-controls/issues/37

• [x] Test

[Lovinity]

Functionality expanded to disallow queuing track requests unless on the air, and disallowing issuing discipline against website visitors unless they are on the air.

[Lovinity]

Functionality expanded more to disallow adding manual log entries unless on the air