Add a data correction to allow changing of the lender reference.
Move DataCorrection presenters into their own sub-directory.
Move data correction specs into separate files.
Normalise copy across data corrections.
Include lender reference data corrections in the
LoanModification#changes.
Allow lender's to change their loan reference at the guarantee step.
Merge pull request #253 from alphagov/add-lender-reference-data-correction

Add Lender Reference Data Correction