V2: Using strong_parameters instead of param_rules

Switching to strong_params as param_rules has some limitations:

1. It doesn't handle nested params
2. It doesn't filter params (on `update`, angular is sending the entire GET structure with candlepin, pulp data which we need to filter out)

Instead of fixing it and then dumping it later (once foreman adopts strong_params or Rails 4), I recommend strong_params.