fix the thumbnail bug for images excpet jpg
fix the discussion link bug in lesson attachement page
fix the attachments and discussion count updating problem
custom the title of file uploader
refactor attachement model
implement remove function of attachement
add authentication for removing attachement
refactor CommentResource and AttachmentResource
refactor task resource
The production section in Gemfile use pg. Should not add options to migration
add publisher test for integration
Add user and publiser factory definition.
Integration test for signup.
add the failed case for signup integration tests.
pass the blind publisher test
More cases for sigup process.
Add integration test for login and logout.
ooops, use the correct password.
Refactor Publisher logic including controller/model/view
Merge branch 'refactor_publishers' of github.com:pragmaticly/re-education into refactor_publishers

Conflicts:
	Gemfile.lock
	app/controllers/application_controller.rb