Allow user based conditions to be set as user field = value

[brendanheywood]

Extending #38

ie we could do id=7 or idnumber=SN12345 or customfield_favcolor=blue

[bozicm]

Would this proposal include custom user fields too? For example: join the "beta" users program checkbox.

[brendanheywood]

Yes that's a great idea and we should get it almost for free