[WIP] Feature/input filter ui

Provides form validation handling, via the following:

- `submit` events on forms marked with the `ag-form` directive cause all inputs, buttons, and selects to be disabled.
- `ag-form` exposes 3 events:
  - `ag-form-submit-complete`, which, when triggered, will re-enable all inputs, buttons, and selects
  - `ag-form-validation-errors`, which, when triggered, will accept the provided error response, parse for validation error messages, and push them into a list group below the form.
  - `ag-form-validation-errors-clear`, which, when triggered, will remove any validation error message list groups in the form.
- a new service, `agFormHandler`, provides two methods, `resetForm(scope)` and `reportError(error, scope)`, which can be used within controllers to clear forms and report form validation errors. `reportError()` checks if the API call returned a 400 or 422 response, and, if so, injects validation error messages below the last element of the form; otherwise, it only raises a flash error message.

## Todo

- [x] REST service update
- [x] RPC service update
- [x] Input filter creation/update
- [x] Documentation creation/update
- [ ] Authorization creation/update