Update browser_helper.rb and warn for old Firefox and Safari
Use 'browser' gem for detection instead of custom regex
Update activity-monitor to use gem 'browser' instead of 'user_agent_parser'
Fix activity-monitor and lib/cdo extension
Add free play links to header
Tweak icon metrics
Checkpoint
Free play links for student dashboard
Code review feedback
Add hand cursor again to video play button.
Add unit tests for free play link helper
Merge branch 'staging' of github.com:code-dot-org/code-dot-org into staging
Code review feedback
Merge branch 'staging' of github.com:code-dot-org/code-dot-org into staging

Conflicts:
	pegasus/sites.v3/hourofcode.com/public/index.haml
Feedback from @breville (make buttons purple)
Merge branch 'staging' of github.com:code-dot-org/code-dot-org into staging
Prizes link next to form on hourofcode.com
Code review feedback
Display % completed in employee engagement landing page.
Merge branch 'staging' of github.com:code-dot-org/code-dot-org into staging