Clean before building

[gaearon]

Seems like there's an extra file in dist right now because we don't clean before build.

[mikekidder]

I can switch react-redux to use npm tasks like redux, if you like.
That will take of this extra build as well.

[gaearon]

Yes, this would be appreciated.

[mikekidder]

PR #19 is ready for review...

[gaearon]

Fixed by #19.