use setting in models/subjCodes.js to set hidden codes

[kenirwin]

e.g.: We currently suppress non-matriculating students (0000) in handleRequest.js

We should instead have an optional suppressSubject field setting in subjCodes.js, easier to suppress a bunch of them and not specify it in the code e.g.

  {
    name: 'Non-Matriculated',
    majorCode: '0000',
    majorName: 'Non-Matriculated',
    libguides: null,
    suppressSubject: true
  },