Merge pull request #689 from code-dot-org/test

DTP
tests
change sharing urls again since they were broken
fix share images for special script
Don't automigrate datamapper on every load, only do it during rake db:migrate
Merge pull request #702 from code-dot-org/test

DTP
Merge pull request #716 from code-dot-org/test

DTP
Merge branch 'production' of github.com:code-dot-org/code-dot-org into test