Upgrade dependencies to React 0.11

Because of the *peer dependencies* requirements, *react-router-component* can't currently be installed with React 0.11. This change upgrades the `package.json` dependencies to React 0.11 and a newer version of *react-async* that also depends on React 0.11.

**This change does not fix any incompatibilities (see #66), simply makes it possible to `npm install` this module alongside React 0.11.**