Rescue RequestDataExtractor#rollbar_ip so it doesn't crash.

[jondeandres]

For example when a IpSpoofAttackError exception is raised.

We were having the next unexpected behavior:

1. An attacker or some proxy configuration performs a suspicious request.
2. In https://github.com/rails/rails/blob/master/actionpack/lib/action_dispatch/middleware/remote_ip.rb#L125 is raised a IpSpoofAttackError exception..
3. Our middleware initializes the reporting of the exception.
4. Our user_ip extraction crashes for the same reason that the app crashed, trying to get the client ip, with a IpSpoofAttackError exception.