Hardcode npm binary reference.

npm.bin seems to return relative to cwd, not relative to
the actual npm install instantiating the call.
Unlikely to change anyway.
Set up npm test
Handle ninja ls edge cases. Extract common code.

Uniques would show up.
Wrong names would appear if folder does not match package name.
Install drivers to folder specified by package.json name
Correct uninstall description.
Fix exit uninstall exit message.
Make test slightly more assertive.
Add ninja uninstall test.