Issue #68 Rework event form dom, responsive

Organize dom of event form using bootstrap grid system so that when
the form collapses its size responsively, it maintains its shape.

Make each row of the form a row type div. Use small column sizes for
form elements to prevent inputs from going under labels until a
very small screen size.

Make the event form a container type.
Issue #68 Add error message spans

Add spans for error messages on each of the event form fields.