remove npm package during Demeteorizer.prototype.findDependencies

[BretFisher]

npm is not needed as a dependency since it's included with node... and now it's hanging up npm install after a demeteorizer because current is 1.3.2 (for 10.x branch) and the package.json is asking for 1.2.2 which causes a failure on npm install.

The fix would be to watch incoming dependencies during folder search and if it was npm, to drop it.

There may be a cleaner way, but I'm working on a fix now.

[BretFisher]

fixed by commit 4c399d1