attempt to pre-populate the course id field in the registration form, if possible. Fixes #131w
add classes to give parsons problem the same look and feel as other self-check question types
replace 'reset' and 'show feedback' links with bootstrap-styled buttons
move parsons problem instructions into alert div
fix #128
Merge pull request #132 from isaacdontjelindell/course-id-for-registration

attempt to pre-populate the course id field in the registration form, if possible.
Merge pull request #134 from isaacdontjelindell/bootstrap-integration

Make Parsons problems have same background and look as other question types; fix broken link
tweak user controller to also capture the course when no _next is present.