Issue 716 - improve form validation/ui

[Simon-Carr]

1. Enable client side validation to prevent postback of text chars into quantity field (should there be a min quantity?).
2. Added small js function to restrict input to 0-9 keys only.
3. Make input classes consistent (add input-text where appropriate).
4. Correct inconsistent button styling (fix remove button styling where appropriate).
5. Make date-pickers more obvious by adding icon.

I'm not sure if this project is active/being maintained or not.....