Move classnames dependency to peerdependencies

package.json

@@ -44,6 +44,7 @@
   ],
   "license": "MIT",
   "peerDependencies": {
+    "classnames": "^2.2.0",
     "react": "^0.14",
     "react-dom": "^0.14.0",
     "react-addons-css-transition-group": "^0.14.0",
@@ -57,7 +58,6 @@
     "babel-loader": "^5.3.2",
     "babel-plugin-react-transform": "^1.1.1",
     "bluebird": "^3.0.5",
-    "classnames": "^2.2.0",
     "core-js": "^1.2.6",
     "cpx": "^1.2.1",
     "cross-env": "^1.0.4",