Pin child modules to tighter semver ranges

Author: brianc

package.json

@@ -22,8 +22,8 @@
     "packet-reader": "0.3.1",
     "js-string-escape": "1.0.1",
     "pg-connection-string": "0.1.3",
-    "pg-pool": "2.*",
-    "pg-types": "1.*",
+    "pg-pool": "~2.0.3",
+    "pg-types": "~1.12.1",
     "pgpass": "1.x",
     "semver": "4.3.2"
   },