Fix problem with node_modules in home directory

I had someone at a workshop run npm init in their home directory. Even though they changed directory to `tessel-code` later, `npm install` will look a few directories up for a package.json file and put node_modules in there. This being the home directory, npm actually refuses to use ~/node_modules when running (but not install).
Merge pull request #44 from garrows/patch-1

Fix problem with node_modules in home directory