Restructure

restructuring as suggested in CodeCatalyst/promise-as3#9 

- the build.xml was originally created by @ThomasBurleson and modified by me 

- as I don't know how to get all the changes in from his fork https://github.com/ThomasBurleson/promise-as3 through all those git branches, I just started from the current CodeCatalyst:master and did what was suggested in https://github.com/CodeCatalyst/promise-as3/issues/9#issuecomment-18420178
(still missing the executon of the unittest stuff from ant)

I hope that helps to join the effords that are put into this great library.