Sending events with symbols breaks in various ways

[dbenamy]

Looks like it's because https://github.com/getsentry/raven-ruby/blob/master/lib/raven/processor/utf8conversion.rb#L19 calls .respond_to?(:encoding) to figure out if it should ultimately call encode.

Could that be .respond_to?(:encode)?

[nateberkopec]

Closed by #241, but the long term fix here is #242