do not reveal passphrase and certificate for iOS variants AGPUSH-662

* https://issues.jboss.org/browse/AGPUSH-662
* + fix variant-details
Android is handled here:
https://github.com/lfryc/aerogear-unifiedpush-server/blob/AGPUSH-662/admin-ui/app/directives/variant-details.html#L31

This assumess that different variant types have distinct fields, or at least those we use for decision here.

The problem here is that empty certificate passphrase is sent from the server, so we can't base this decision on passphrase. `variant.production` is mandatory for iOS variants on other hand.

The second part, bellow, is just UX improvement:
`Type: production` instead of 'Production Key: true`