add gradle build script to allow the library to be packaged as aar file ...

...wich includes all resources. It also allows to get third party dependency from maven repository and the project to be imported into android studio.

You need to install gradle 1.9 (http://services.gradle.org/distributions/gradle-1.9-bin.zip) to build the project with the command line

gradle assemble

then the produced artefact is

build\libs\android-smsmms.aar

The ion source stuff is kept to get the compatibility with ant build but is not used by gradle that get dependencies from maven central repository. Ion directory can be fully deleted.