Remove dependencies on npm and n

Neither package is actually require()'d in the code. strider-node expects
these modules to be installed globally, which the dependency wouldn't do
anyway. All these dependencies do, is pull in code that is never used and
block installation on Windows.

Author: oliversalzburg

package.json

@@ -17,8 +17,6 @@
   "author": "Peter Braden",
   "license": "BSD",
   "dependencies": {
-    "npm": "^2.7.1",
-    "n": "^2.1.0",
     "md5": "^2.0.0",
     "async": "^1.0.0",
     "fs-extra": "^0.8.1"