Add a link to Contact Us to Twitter page.
Student can't see other student's correction data.
Show cost in the free correction confirmation page.
Install Sassy Buttons.
Fix button position.
Update free correction page.
Rename text-shadow mixin because it's used by Compass.
Use Compass clearfix.
A new student has 2000 initial points.
Merge branch 'master' into update_site_design
Update free correction page.