Renamed 'live' to 'preview'.

Makes more sense:
1) Use "git push" to push to origin; the page will be visible
   under http://spikesagal.github.io/require/preview/
2) Use "git subtree push --prefix=preview jsrequire.github.io master";
   the page will now push to http://jsrequire.github.io/ -- horaay!