Crabgrass modifications for a demo page with video and a pad

The pad is not really integrated in with the users, groups and pages in Crabgrass, the video is an static url and the pad timeline isn’t synchronized with the video.

It’s intended to show just the idea and further develop Crabgrass pages with videos that can be associated to pads and to have annotations synchronized with videos/streamings.

For a full integration with Etherpad-lite see Etherpad-lite integration in Crabgrass

Files added/modified

app/controllers/pad_demo_controller.rb
app/helpers/pad_demo_helper.rb
app/views/pad_demo/show.html.erb
config/initializers/etherpad-lite.rb
config/routes.rb
test/functional/pad_demo_controller_test.rb
test/unit/pad_demo_helper_test.rb