gradle build fails on mac

some of the mac is forced to use Java 8 and Scala plugin does on
Gradle 1.12 does not work with Java 8. Gradle has fixed the issue on
2.0 version.

Added a task to cleanup the config directory files so that changes to
stores.xml will take effect.
Disable incremental compilation for Scala

Scala build intermittently fails with the error on mac

FAILURE: Build failed with an exception.

    What went wrong:
    Could not resolve all dependencies for configuration ':zinc'.
    > Could not find org.scala-lang:scala-library:2.10.2.

This is caused by incremental zinc compilation. Given the fact that
scala is very rarely used the intermittent failure is very hard to
workaround.
Four node and two node configs

two configurations for local testing. I found it helpful for testing
some of the scenarios. Editing them on multiple machines is painful and
others could use this for testing.