Missing expectMultiPart(true); in Scala docs

When you make a Multipart Form Upload you have to call "request.expectMultiPart(true);" before you register the handler. This line of code is currently missing in the Scala docs. I added it to both code examples like it is in the Java docs.
Merge pull request #33 from Zwergal/patch-1

Missing expectMultiPart(true); in Scala docs