removes renegade quote in markup string

Note to self: the whole chunk of code here can probably be removed,
actually.. but that's for another pull request.

Author: usmonster

js/jquery.fn.gantt.js

@@ -658,7 +658,7 @@
                         // Last month
                         monthArr.push(
                             '<div class="row header month" style="width: '
-                            + tools.getCellSize() * daysInMonth + 'px">"<div class="fn-label">'
+                            + tools.getCellSize() * daysInMonth + 'px"><div class="fn-label">'
                             + settings.months[month]
                             + '</div></div>');