Expertiza project E723 - Fix review versioning
1. Added logic to check whether a review is currently valid. A review is not valid if there was a submission after the review and the next review stage has reached
2. Changed score calculation logic. Scores of stale review will not be considered for final average
3. Added option to delete links from submitted content
Fixes typo in submitted_content_controller.rb.
Added code to display one radio button checked by default for hyperlinks listed on 'Your Work' page.
Expertiza project E723 - Fix review versioning - Refactoring
Moved is_valid function to response model
1. Added unit test cases for score invalidation logic
2. Renamed is_valid_for_score_calculation to is_valid_for_score_calculation?
Added test case for verifying removal of hyperlinks.
Merge https://github.com/chelseaarjun/expertiza into E723

Conflicts:
	app/models/response.rb
	app/models/score.rb
	app/views/submitted_content/_hyperlink.html.erb