Dependency cleanup (#94)

* [fixed] Remove duplicate dependency

* [fixed] Demote React to a peer dependency

Having React as a direct dependency can cause multiple versions of React
to be bundled in applications that depend on a React version that doesn't
match `^0.14.7`.

* [changed] Allow both 0.14 and 15 versions of React

package.json

@@ -35,8 +35,9 @@
     "mocha": "~2.4.5",
     "mocha-jsdom": "^1.1.0",
     "rackt-cli": "^0.4.0",
-    "react": "^0.14.0",
-    "react-addons-test-utils": "^0.14.7"
+    "react": "^0.14.7",
+    "react-addons-test-utils": "^0.14.7",
+    "react-dom": "^0.14.7"
   },
   "tags": [
     "react",
@@ -46,9 +47,9 @@
   ],
   "keywords": [],
   "dependencies": {
-    "babel-preset-es2015": "^6.5.0",
-    "dom-scroll-into-view": "1.0.1",
-    "react": "^0.14.7",
-    "react-dom": "^0.14.7"
+    "dom-scroll-into-view": "1.0.1"
+  },
+  "peerDependencies": {
+    "react": "^0.14.7 || ^15.0.0-0"
   }
 }