Create acw.lua

This is a widget which uses some APIs to give Bitcoin and Dogecoin prices in USD.

It is derived partly from this: http://awesome.naquadah.org/wiki/Bitcoin_Price_Widget. I do not know who the authors are and from what I can tell any content on the wiki is Creative Commons Attribution 3.0 Unported License. I'm not sure if it can be relicensed or not.