Some better error screens
Replace welcome email with new template
Add in mailer previews
Update welcome_email.html.erb
Update welcome_email.html.erb
Add in grade selector
remove lib/ruby-client which is now out of date
Remove queue classic, capistrano and latin american file
Switch to redis for caching
add redis-rails gem too.
Fix date picker
Merge branch 'develop' of github.com:empirical-org/Empirical-Core into develop
Resolve merge conflicts
Merge branch 'features/better_intro_email' into develop

Conflicts:
	db/schema.rb
Merge pull request #335 from empirical-org/features/better_intro_email

Features/better intro email
latest migration
potential fix for classroom manager view