Moving Cairo installation instructions out to root README to help future developers with setup, and added OSX step for making sure XCode Command-Line tools are current.
Merge branch 'staging' of https://github.com/code-dot-org/code-dot-org into staging
End of space at level names can cause collisions
Merge branch 'test' into staging
Fix prize anchor link
Merge pull request #809 from code-dot-org/fix_anchor_link

Fix prize anchor link
Fix share image cache lookup from redis
code.org translations 12/9
Merge branch 'staging' of github.com:code-dot-org/code-dot-org into staging