Added devDependancies for missing modules needed to run tests.

Change-Id: I25a3c03ea975a2bdca2add4b058049c38898606a
Reviewed-on: http://review.couchbase.org/28648
Tested-by: Brett Lawson <brett19@gmail.com>
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>

package.json

@@ -11,6 +11,11 @@
     "dependencies": {
       "bindings": "~1.0.0"
     },
+    "devDependencies": {
+      "async": "0.2.9",
+      "longjohn": "0.2.1",
+      "underscore": "1.5.1"
+    },
     "repository" : { "type" : "git", "url" : "http://github.com/couchbase/couchnode.git" },
     "version": "0.0.12",
     "gypfile": true