First pass at client side validation

Added required if question is marked as mandatory
Also preliminary support for type checking (:float, :integer, :time)
Using jqueryvalidation.org for client side validation

https://github.com/NUBIC/surveyor/issues/34
notes in comment
Use required class instead of surveyor_required
Merge pull request #4 from HeHStudy/34_support-validations

UI validations