Add attempeted at field in grading summary
Allow line breaks in achievement descriptions (show as a list)
remove empty li(s)
remove chomp in the if statement
Using rich html editor to implement
put css style in custom.css.scss
Merge pull request #201 from wangqiang1208/features/achievements-list

Allow line breaks in achievement descriptions (show as a list)
Implement bulk download for missions
[migrations] remove and fix invalid migration files

db:migrate run without error for empty database
[Migration] remove old_tags table (no longer in use)
Merge pull request #202 from wangqiang1208/buggfixing/bulk-download

Fix bulk download for missions
Merge branch 'development' of github.com:Coursemology/coursemology.org into development
add a new saved_at field in submission table
Add last save field to mission grading
Merge remote-tracking branch 'upstream/development' into features/mission-date
Merge branch 'features/mission-date' of https://github.com/wangqiang1208/coursemology.org into features/mission-date

Conflicts:
	app/views/assessment/gradings/_summary.html.erb
Merge pull request #200 from wangqiang1208/features/mission-date

Add attempeted at field in grading summary
added basic feature to highlight words for essay questions
basic refactoring, added jquery highlight library
renaming classes and styling