Mike login page

The homepage is responsible to save the loginbox state so that data entered is not lost if the overlay is closed then reopened
![image](https://cloud.githubusercontent.com/assets/4157103/4431349/8749760c-4662-11e4-8b9d-fa656abfd81d.png)

You inlined all of `errorMessage`'s definition, perhaps it could have been put here directly? Then again, perhaps you prefer the `setState` call to only have one line per state variable. Just curious.