Support to Tumblr elements

I added a .not() selector to your plugin but it must be inlcuded in the options. (I am not able to do that unfortunatelly).

The .not selector is useful not to select some elements, especially on tumblr themes. On tumblr themes there are some elements that it is better not to touch and this plugin touches these elements. You cound add an option like `ignore: undefined` which will be defined later on the options. Unfortunatelly I am not able to add this feature to your plugin but I (and all tumblr themes designers) will be grateful. Your plugin is the only one that works!!