Add Meltdown editor
I did not add the Meltdown support for IE 7 and 8
Update PHP Markdown Extra to 1.2.8
Fix Meltdown toolbar bug
Updated Meltdown
Improving toolbar buttons actions
Merge pull request #8 from jlgrall/add-meltdown

Add Meltdown editor
Merge pull request #9 from jlgrall/update-phpmarkdownextra

Update PHP Markdown Extra to 1.2.8