Address#empty?

- Address#empty? is true unless all attributes are present.
- RespondentForm#worked_at_different_address is true unless
  Repsondent#work_address is empty?
FeeGroupReference.create

Calls Jadu API to obtain a fee group reference for this claim
Rails 4.2.0.beta1
Fix Rails 4.2 breakage re attribute type coercion
Silence deprecation warning

The column_for_attribute deprecation warning doesn't really impact
this usage.
Hook up Fee Group Reference background processing
Add stub FGR service to development
Revert "Address#empty?"

This reverts commit 555c5be7acb38b463857f52c6fc0a3bd2a827d4f.
Merge pull request #30 from ministryofjustice/fee-group-reference

Fee group reference