Merge pull request #287 from nanan9177/blockly_fix

Speeding up the share page.
Make "free draw" levels show as completed, perfect [Fixes #66023540]
Major UI overhaul of learn.code.org.
Merge pull request #288 from code-dot-org/free_play_dashboard_bug

Make "free draw" levels show as completed, perfect [Fixes #66023540]
enable flappy bird
Merge pull request #289 from code-dot-org/learnui

Major UI overhaul of learn.code.org.
Change 'Sign up' heading to 'Student sign up'.
Update readme with mailcatcher instructions.
Merge pull request #290 from code-dot-org/flappy

enable bird game
Quick fix for activities with nil level_source_id.