Remove non static resource requests
Removes ResourceTypeFormSet from class edit page

This formset was always being instantiated as an empty formset.

TODO: Can the formset be completely removed from the code?
Improvements to NewResourceRequest model
Adds NewResourceRequestForm

Also adds AmountOrPercentField, for use with form fields that can be
either integers or integer percentages.
Adds test view for NewResourceRequestForm
Adds ExactlyOneNotEmptyValidator