Bump Akka version to 2.3.2

Quoth @rkuhn:

> seeing that you are cutting a Scala release, we’ll need to
> decide on which Akka version to bundle with it. 2.3.0 has
> some remoting bugs which we’d like to leave behind

Given the difficult of overriding the bundled Akka version
from the Scala script runner (SI-8472), we've deemed it
worthwhile to bump the Akka version before releasing 2.11.0.

versions.properties

@@ -22,7 +22,7 @@ scala-parser-combinators.version.number=1.0.1
 scala-continuations-plugin.version.number=1.0.1
 scala-continuations-library.version.number=1.0.1
 scala-swing.version.number=1.0.1
-akka-actor.version.number=2.3.0
+akka-actor.version.number=2.3.2
 actors-migration.version.number=1.1.0
 
 # external modules, used internally (not shipped)