Implements streaming CSVs.

Allows unlimited downloads of CSV data using ActiveRecord batch APIs and ActionController response streaming.

Works on Rails 3.2+
Actually pass the options to generate_line.
Make the meat and potatoes of streaming protected.
Add no-cache header to streaming CSV responses.
Disable downstream response buffering of stream
Add header_action method for panels
Use Capybara to better test panel rendering
Use latest cucumber-rails release
give optional deps in Gemfile their own section
don't specify a version for Devise in the Gemfile
#3005 appears to be resolved!

…though we have to specify a version for sass-rails (#3093)
update sass-rails requirement to work with Rails 3

#3005, #3093
test Ruby 2.1.2
add rspec filter 'focus' and 'skip'
specs for MethodOrProcHelper#render_or_call_method_or_proc_on
Fix for #3155
test fix for #3155
specs for MethodOrProcHelper#render_in_context
check the return of MethodOrProcHelper#render_or_call_method_or_proc_on and #render_in_context
Merge pull request #3158 from timoschilling/missing_specs

Missing specs for MethodOrProcHelper