Rename scalastyle_config.xml to scalastyle-config.xml

Author: bhermann

project/scalastyle_config.xml renamed to project/scalastyle-config.xml

@@ -146,4 +146,4 @@
   </parameters>
  </check>
  <check level="warning" class="org.scalastyle.scalariform.ImportGroupingChecker" enabled="true"></check>
-</scalastyle>
+</scalastyle>