restructuring as suggested in CodeCatalyst/promise-as3#9
- the build.xml was originally created by @ThomasBurleson and modiefied by me
- as I don't know how to get all the changes in from his fork ThomasBurleson/promise-as3 through all those git branches I just started from the current master and did what was suggested in https://github.com/CodeCatalyst/promise-as3/issues/9#issuecomment-18420178