Fix typo when no errors are found.

When no errors are found by jslint, the package prints the message: "No errors was found!"

That should read: "No errors were found!"

![screen shot 2014-03-10 at 4 31 22 pm](https://f.cloud.github.com/assets/1429850/2378939/c1b5e6f2-a894-11e3-97b0-efd2c272ba3b.png)