Fix old survey event can't be edited

It is because the com_req and self_eval fields are required. Disabled
those validation for survey event
Fix the incorrect URL in test
fixed checkbox css problem for "Zero Mark" - rubric

Conflicts:

	app/webroot/css/ipeer.css
fixed checkbox css problem for "Zero Mark" - rubric

Conflicts:

	app/webroot/css/ipeer.css
Update/fix test cases for penalty/events.

Expected data for penalty display has to be updated due to the fix to
Penalty data where it was removing 1 entry from the Penalty data on each
query.

Events model didn't need the variable type declaration.
Add check for PHP's GD Extension in installer.

It's required to generate the images for the survey progress bar.
Remove javascript popup when submit evals.

There's a popup message that shows up everytime the submit button is
pressed on an evaluation, it was annoying, so was removed.
Merge branch 'hotfix' into dev