Issue #68 Remove default subkast

A default subkast causes the form to show that subkast on load. Remove this
default subkast so that the form will show --- at first.
Issue #68 Add event validation rules

Event now has validate function which can prove if the event is valid
to be saved.

Rules are:
  Must have a name
  Must have a name under 100 characters
  Must have a subkast
  Must have a datetime
Issue #68 Spinner to show up after validate

Refactor spinner and save button into their own views.
Add a region to the event form for placing the save button and spinner.
Only show the spinner when the event has been validated.