Remove pin on react 15.3 and bump draft-js-export-html instead

draft-js-export-html have fixed the incompatibility with react 15.4, so we can
now update.

Author: richvdh

package.json

@@ -47,7 +47,7 @@
     "browser-request": "^0.3.3",
     "classnames": "^2.1.2",
     "draft-js": "^0.8.1",
-    "draft-js-export-html": "^0.4.0",
+    "draft-js-export-html": "^0.5.0",
     "draft-js-export-markdown": "^0.2.0",
     "emojione": "2.2.3",
     "filesize": "^3.1.2",
@@ -62,9 +62,9 @@
     "matrix-js-sdk": "matrix-org/matrix-js-sdk#develop",
     "optimist": "^0.6.1",
     "q": "^1.4.1",
-    "react": "15.3.2",
+    "react": "^15.4.0",
     "react-addons-css-transition-group": "15.3.2",
-    "react-dom": "15.3.2",
+    "react-dom": "^15.4.0",
     "react-gemini-scrollbar": "matrix-org/react-gemini-scrollbar#5e97aef",
     "sanitize-html": "^1.11.1",
     "velocity-vector": "vector-im/velocity#059e3b2",
@@ -100,7 +100,7 @@
     "karma-webpack": "^1.7.0",
     "mocha": "^2.4.5",
     "phantomjs-prebuilt": "^2.1.7",
-    "react-addons-test-utils": "15.3.2",
+    "react-addons-test-utils": "^15.4.0",
     "require-json": "0.0.1",
     "rimraf": "^2.4.3",
     "sinon": "^1.17.3",