Twenty Fourteen: file cleanup and organization

[lancewillett]

Let's clean things up a bit now that we have more files, and are closer to release.

• Rename fonts to genericons
• Create a css directory and move all CSS except style.css into it
• Create a page-templates directory and move page templates into it

[lancewillett]

In 26103:

Twenty Fourteen: rename fonts to genericons. See #25929.

[lancewillett]

In 26104:

Twenty Fourteen: move CSS files except for rtl.css and style.css into new css directory. See #25929.

[lancewillett]

In 26105:

Twenty Fourteen: move page templates into their own directory. See #25929.

[lancewillett]

Leaving open so we can test more, make sure nothing broke during these moves.

[lancewillett]

Things are in good shape, we can re-open if any issues pop up in testing.