Support multi point version name.

Hi, this plugin is awesome.

But it doesn’t work in the following environments.

- Android Studio 1.0.0
- `com.android.tools.build:gradle:1.0.0`
- gradle 2.2.1 (gradle plugin 1.0.0 required gradle 2.2.1 or later.)

I faced error below.

`Error:(25, 0) Cause: multiple points`

The cause of this error is judgement of gradle version on `RoboSpockAction.groovy`.
I try to fix it.

thanks.