Fix double encoding in main reports block

Conflicts:

	application/i18n
Set HTMLPurifier to user application/cache for serializer path

Avoids adding another writable directory.
Quick fix for fatal errors in VideoEmbed library

Cases where video embed wasn't recognised weren't being handled.
Fix error in helpers/reports.php when uploading to CDN #1099
Fix double encoding in main reports block
Set default values for allowed html and iframesi #1056

This avoids errors if upgraders don't update config.php

Conflicts:

	application/i18n
Merge remote branch 'upstream/master' into develop