Revert "fix build to work with gradle 2.0."

This reverts commit 7fa19d57033552b9bd3420989ca1d078084a9ed0.

We're not ready to build with 2.0 yet because the groovy versions
are incompatibile with anyone using 1.12 or earlier
Upgrade to Gradle 1.12, clean up build

Removed Guava dependency
Removed Idea gradle plugin
Release 1.9.7