During duplication, skip validations (with warning).

This ensures duplication works even if the activity being duplicated is invalid for some reason (most likely bad markup). Should fix [#62054562].

https://www.pivotaltracker.com/story/show/62054562
More validation overriding to ensure duplication.

[#62054562] This is looking at the possibility that the issue is actually in *page* saving, not *activity* saving.

https://www.pivotaltracker.com/story/show/62054562
Better fix to override acts_as_list
Gemfile and ruby version tweaks (Travis)
More Travis config tweaks

See http://about.travis-ci.org/docs/user/languages/ruby/#Dependency-Management
Merge branch 'refs/heads/master' into portal-publications