Reenable ScalaStyle on build for Cypher

The list of enabled rules is at this point minimal compared to the old config
but every violation is treated as an error and fails the build.
The next steps for this will be to keep adding more rules one by one
and fixing the existing occurrences.
Merge pull request #2087 from jakub-/scalastyle

Reenable ScalaStyle on build for Cypher