User creation functionality is complete. I also made the handling of
errors more pretty-looking. Other changes:
- Changed the Mailer sender address.
- Deleted admin.html and renamed list.jsp to admin.jsp.
- I integrated user.html into the workflow.

To do:
- Make the file upload work from index.jsp.
Capitalized some words. Also, see previous commit.

To do:
- Display list of submissions.