Improve running tests from IntelliJ

Hi,

I worked on a couple improvements for running tests within IntelliJ. We have been using this version of the plugin at Pivotal when working on Cloud Foundry go components.

 * removed the make task from the default Go test runner which was causing issues in some cases.
 * fixed running focused tests from a package ending in "_test" so that the package name to use is inferred correctly.

Thanks,
Damien