Allows for $0 options in extracosts.

Makes the Student Extra Costs module work with line item types that have
$0 options.

Adds a extra_costs_done Record to keep track of when a student has
completed the module.

Also adds a reset button for each group of radio buttons on the form.

Resolves Github Issue #1118.
(cherry picked from commit b231260f73e42d6dccac98b03980e5c715b0db23)
Merge pull request #1134 from learning-unlimited/extra-costs-fix-on-stable-feb14

Allows for $0 options in extracosts.