Relax `should` dependency version.
Add sinon, with test/common shared import.
Store cluster and process instance references to facilitate test stubs.
Add pretest jshint.
Add sinon to test globals.
Don't test core modules, test our code. Woo sinon.
Merge pull request #30 from zillow/fix-destroy-async

Fix tests for node v0.11.x
Merge branch 'master' into errorhandler-caching