Revert "Merge pull request #28 from mongodb-js/greenkeeper-ampersand-collection-2.0.0"

This reverts commit 19295c3, reversing
changes made to ef6faac.

Author: imlucas

package.json

@@ -23,7 +23,7 @@
     "check"
   ],
   "dependencies": {
-    "ampersand-collection": "^2.0.0",
+    "ampersand-collection": "^1.6.1",
     "ampersand-model": "^6.0.2",
     "ampersand-rest-collection": "^5.0.0",
     "async": "^1.5.2",