use utc datetimes in iso8601 for posts and pages

I've been playing with Octopress for a few weeks now to use for my blog and recently I noticed dates and times when using 'rake preview' were off from what I was expecting. The issue for me was that my desktop had a different (and wrong) timezone compared to my laptop. I see that currently, the rake tasks just dump year, month, day, hours, and minutes into pages and posts, and it seems the current timezone is assumed when the html is generated . I modified the new_post and new_page rake tasks to use utc and iso8601, and added a task to update old non-iso8601 page and posts. Then I added a javascript library ([moment.js](http://momentjs.com)) in order to adjust dates and times to the visitors timezone. I'm sure this is an incredibly rare and relatively unimportant issue, but I figured this makes ones blog a little more universal (err maybe just global).