Update mime.php to current reccomendations

Update mime.php to add webm and implement current mime recommendations for the ogg, oga, ogv & ogx containers:

http://www.ietf.org/rfc/rfc5334.txt
Updated highlightSearch() to respect source string's case
Merge pull request #1028 from JeffPaetkau/patch-2

Update mime.php to current reccomendations
Merge branch 'master' of github.com:concrete5/concrete5
validation on set items per page
bulk SEO vulnerability fix