v1.3.0 -> v1.4.0

Updating Polymer to v1.6.0 because of #144.

Author: bicknellr

bower.json

@@ -1,6 +1,6 @@
 {
   "name": "paper-checkbox",
-  "version": "1.3.0",
+  "version": "1.4.0",
   "description": "A material design checkbox",
   "authors": [
     "The Polymer Authors"
@@ -21,7 +21,7 @@
   "homepage": "https://github.com/PolymerElements/paper-checkbox",
   "ignore": [],
   "dependencies": {
-    "polymer": "Polymer/polymer#^1.1.0",
+    "polymer": "Polymer/polymer#^1.6.0",
     "iron-checked-element-behavior": "PolymerElements/iron-checked-element-behavior#^1.0.0",
     "paper-behaviors": "PolymerElements/paper-behaviors#^1.0.0",
     "paper-ripple": "PolymerElements/paper-ripple#^1.0.0",