Change "npm test" to call mocha directly

Rework the test script to call directly mocha and skip Makefile. This
allows CI enviroments to detect that this module is using Mocha as
the test runner.

package.json

@@ -26,7 +26,7 @@
     "clean": "make clean",
     "help": "make help",
     "refresh": "make refresh",
-    "test": "make test"
+    "test": "NO_DEPRECATION=loopback-datasource-juggler mocha"
   },
   "engines": [
     "node >= 0.6"