Fix #119:
  - Strips commas from user input on pay fields
  - Validates numericality of pay fields
  - Changes payment field's input type to text (browser doesn't
    even send non-numeric values)

Closes #119.
updated pay fields by adding back the pound sign and alignment which was somehow lost
Merge pull request #259 from ministryofjustice/bug-fix/validate-numericality-of-employment-form-pay-fields

Fix #119: