Scrolling on old Androids

Hey @jakiestfu, I just spent a couple of hours trying to get iScroll to work, so that scrolling on elements with overflow:auto would work on Android 2.3 and lower.

After lots of cursing, I finally gave up on iScroll for the day, but did some more searching and found @filamentgroup's Overthrow polyfill (https://github.com/filamentgroup/Overthrow), and it just worked, all I had to do was add an "overthrow" class the content area and to the drawer.

Recommend changing the recommendation in the Readme, maybe it'll save others some time. Thanks again for the great script.

Start with the README recommendation for scrolling on Android 2.3 and lower, then review the issue's Overthrow reference and the reported use of an "overthrow" class on the content area and drawer. Update the recommendation to reflect the working approach and verify that the README clearly explains where it applies.

Written by the indexing model from the issue text.