Update of certificate/passphrase on iOS variant impossible

When updating an iOS variant from the UI, the certifacate/passprhase is never updated, because the UI triggers HTTP_PATCH

This hits this part of the server:
https://github.com/aerogear/aerogear-unifiedpush-server/blob/master/jaxrs/src/main/java/org/jboss/aerogear/unifiedpush/rest/registry/applications/iOSVariantEndpoint.java#L112-L116

I think lholmqui@redhat.com added that for update of name/description - but not for file.

File(certificate) and passphrase update should be a HTTP_PUT, which means this part of the server would be invoked:
https://github.com/aerogear/aerogear-unifiedpush-server/blob/master/jaxrs/src/main/java/org/jboss/aerogear/unifiedpush/rest/registry/applications/iOSVariantEndpoint.java#L136-L141