Publish for Scala 2.11.0-M4

Published using `publish-signed`.

With pgp plugin loaded in ~/.sbt/plugins/plugins.sbt:

```
addSbtPlugin("com.typesafe.sbt" % "sbt-pgp" % "0.8")
```

Using sonatype with ~/.ivy2/.credentials:

```
realm=Sonatype Nexus Repository Manager
host=oss.sonatype.org
user=???
password=???
```

Upgraded SBT version to the latest 0.12,
as 0.12.1 had a bug that kept me from publishing.

review by @vjovanov