Improvements to pages/auth/signin.js

[iaincollins]

Improve the componentDidMount() call in pages/auth/signin.js.

Avoid calling setState() in it if possible to avoid re-renders that at not really necessary and definitely don't call this.state directly, that's a typo.

It should look something like this:

  async componentDidMount() {
    const session = new Session()
    const latestSessionData = await session.getSession(true)
  }

The render() function may need to be changed to reference this.props rather than this.state.

[iaincollins]

This has been refactored in the bootstrap branch (which I hope to merge into master soon).