[finishes #73148102]: disable teacher prizes
hide more prize references, update donorschoose URL
update FAQ URL
Merge pull request #806 from code-dot-org/disable_teacher_prizes

[finishes #73148102]: disable teacher prizes [DO NOT MERGE UNTIL 6/15/2014]
Merge pull request #823 from code-dot-org/finished

DTD: disable teacher prizes (hold off on DTP until after 12:00am 6/16/14)