A modest release script

Review by @gkossakowski

I just pushed the first -SNAPSHOT releases

https://oss.sonatype.org/content/repositories/snapshots/org/scala-lang/modules/scala-java8-compat_2.11.0-RC3/
https://oss.sonatype.org/content/repositories/snapshots/org/scala-lang/modules/scala-java8-compat_2.10/