Allow specifying the location of the output swf file inside packaged mobile application.
Note that this change potentially breaks builds; the original implementation packaged the swf file to project.buildDir/output.swf, this implementation places it in the root of the package. In my opinion this is not a good behavior, its not intuitive that the location of the .swf file is packaged with the build directory name.
If this is a problem, I can extend this PR that keeps the old default behavior (should be just a one line change)
mainSwfDir AIR option is read by non-mobile AIR projects too.
Merge pull request #155 from matyasatfp/swf_package_name

Allow specifying the location of the main swf file inside the packaged mobile application. Change default location of swf to root of the package