Add duplicate_of field and keep existing tests passing
Add unit test unit test for duplicate needs
Add `closed` controller method
Merge branch 'master' into merging-duplicates

Conflicts:
	app/controllers/needs_controller.rb
	app/models/need.rb
	test/test_helper.rb
	test/unit/need_test.rb
Code and integration test for closing a need as a duplicate
Show an error if closing a need as a duplicate fails
Add extra functional tests for duplicate needs.
Can't edit a need that is closed

* Redirect to show page if edit url is requested
* Add text to page to show need is closed as a duplicate
* Remove edit button from revisions page if need is closed as a duplicate
Duplicate need shows link to main need
Rename CSS class
Closed need revisions page shows link to main need
Extract close_as method
Extract author_atts method on need model
API adapter call changed to close
API adapter version update to use close method for Need API
Make duplicate_of a protected field
Remove unneccessary test setup
Use prepare_need_params method
Merge branch 'merging-duplicates'