Added Validation and Completion Criteria

Built cross-browser form validation using Bootstrap's Modal dialogs and
a completion message (non-functional currently).

Bug fixes:
- Rendering of Previous and Next buttons now appear on same line in
mobile browsers.
- Container width no longer static across desktop and mobile, will
automatically shrink for mobile displays for easier viewing.
- Container height set to minimum of 300px from a fixed height of 300px,
allowing for mobiles to overflow content.