Merge pull request #150 from MargaretLangley/master

Replacement of double quotes by single quotes where possible
Refactoring cycle forms
Merge branch 'master' of github.com:BCS-io/letting
Refactoring InvoiceText
Padding on form edges instead of book-ending forms with empty columns
Payment new has the same left margin
Payment refactoring
Client View: ID => Property ID
Putting back js class which allows cycle to add due_ons