Add form for bug reporting

Problem/motivation

[ ] Form access is limited to authenticated users
[ ] The form includes a pre-populated "Page on which the issue occurs" field with the URL of the originating page.
[ ] The form includes a generic "describe the problem" text field that is required
[ ] The form includes an optional file uploader, limited to image file types
[ ] The form includes a checkbox for "Contact me with updates about this issue"
[ ] Upon submission, the form will initially email the report, along with context-specific data, to an email address specified in configuration.
[ ] The implemenation should be done in such a way to easily support subsequent integration with Basecamp