This commit adds a check for how much of the table that has scrolled out
of view when showing the overlay. This will hide the overlay again when
a user scrolls past the table.

Now the overlays are properly positioned in Firefox,too.

When handling the scroll event, the plugin now checks whether the table
still exists in the DOM. If not, the registered event handlers are
unregistered.

The events have also been namespaced to avoid unbinding event listeners
outside the plugin by accident.

Mobile Safari on iPhone (not iPad) has a stupid bug that somehow thinks the height of the viewport is the entire screen minus the height of the address bar - even though the address bar scrolls out of view. So, this fix adds 60 pixels to the height if the client is an iPhone.

Every time the plugin is initialized it adds overlay markup to body.
This fix removes it first.

A bug in finding the selected cell caused the overlay categories not to
update their position when scrolling.

New setting allows pushing the overlays away from the viewport edge.

Also include the CSS file when deploying with Bower.
Fixed an issue with naming the distributed files.