Added nanny feature and test
Merge pull request #2 from cubejs/master

Pull the latest update
Used deathQueue to kill the unresponsive worker and create a new successor
Changed the name convention
Added test case and modified test/lib/server.js to support the test case
Added test case to verify the number of workers
Converted the test case to nodeunit test case
Merge pull request #41 from zhuchenwang/master

Added nanny feature and test