Add pry-rails
Add lesson plan entry tests
rescue seen_by_users record unique exptioncaused by threadsafe
s/should//
Merge pull request #279 from jsyeo/jsyeo-lesson-plan-tests

Add lesson plan entry tests
Merge pull request #280 from wangqiang1208/bugfixing/seen-by-user-not-unique

rescue seen_by_users record unique exception caused by threadsafe
Merge pull request #269 from jsyeo/jsyeo-add-pry

Add pry-rails
Use new expect syntax for mission display test.
Resolve merge conflict in spec/factories.rb. Add factory for mission creation and Mission edit tests.
Add tests to check editing of Mission title, description and experience.
Use lecturer use for Mission tests. Use updated course creation method for tests.
Resolve merge conflict with origin branch.