Set minSdkVersion + targetSdkVersion via build.gradle

Without this building with Gradle adds a 'maxSdkVersion' attribute to the manifest. This seems to cause the targetSdkVersion value being ignored. And with a targetSdkVersion value lower than 16 the permissions READ_CONTACTS/WRITE_CONTACTS imply READ_CALL_LOG/WRITE_CALL_LOG. But we don't need/want those permissions.