Safari Flexbox issues

Yes, I know I have this PR made on my master branch. I forgot to make a new branch before starting... woops!

Few notes:

1) Commented out that section in tiles.js as I encountered an issue. Sometimes, self.fetchOrder() will return an array  with null elements. If this happens, the forEach loop will blow up and the page will only render the header. So for now, I commented that code out.

2) Some Safari-specific flexbox stuff was missing from the flexbox less file. Safari uses the -webkit-box syntax, which is not used by any other browser but Opera, IIRC. Also, there is no align-self support in Safari. FUUUU

3) There is still the issue of the border radius + border around the avatar looking completely odd in Safari. Not sure if that would be considered a separte issue though.

I'm on vacay the last week of August, so feel free to fork / hack on / land this while I'm gone, or close if it isn't needed.