Fee calculations

 - Add ClaimFeeCalculator to calculate hearing and application fees
   for jurisdiction 1
 - Add Claim#claimant_count because Law of Demeter
 - Move some specs from models directory into new services directory
Fee calculations:

 - Calculates fees for claim type 2, i.e. non-discrimination and
   non-unfair-dissmissal claims
 - Adds Claim#alleges_discrimination_or_unfair_dismissal? which
   delgates through to ClaimDetail#alleges_discrimination_or_unfair_dismissal?
 - Adds ClaimDetail#alleges_discrimination_or_unfair_dismissal?
Fee remissions

- Add remissions calculations to ClaimFeeCalculator
- Add remissions to form

Closes #25
WAT

A migration somehow went missing. I don't even...

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Merge pull request #26 from ministryofjustice/fee-calculation

Fee calculations
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