Fixing CSS conflict

Adding the !impotant instruction in order to fix some compatibility issue.

The new editor_for_symphony created a bug where the icons would not get displayed.
Compatibility with Symphony 2.5

Your extension is compatible with 2.4 and 2.5beta2 so I guess it's
safe to tag it as such.
Merge pull request #3 from DeuxHuitHuit/compatible

Compatibility with Symphony 2.5
Merge pull request #2 from DeuxHuitHuit/css-fix

Fixing CSS conflict