Update gradle build files so that ABS can be referenced correctly as a gradle subproject

Hi I have updated the gradle build files so that anyone can correctly reference ABS as a gradle subproject.
I followed Xavier's recommendation found here: http://stackoverflow.com/a/16974411.
This means that I have updated settings.gradle as recommended and I also updated each project's build.gradle so that each subproject applies both the buildscript repository and classpath dependency individually. 
Finally I changed the dependency for the support-v4.jar to v13.0+. I know that is not yet available in Maven Central but if someone is building locally I believe the latest version should be used.