Use 13pt as the default font size.

I'm a fan of 13pt rather than 14pt for the default font size, this makes the menu bar slightly more compact, and imo feels easier on the eye.

**Before:**

![screen shot 2013-11-06 at 12 59 21](https://f.cloud.github.com/assets/28017/1482543/e623529e-46e3-11e3-8561-f6f2e26da325.png)

**After:**

![screen shot 2013-11-06 at 12 59 06](https://f.cloud.github.com/assets/28017/1482547/f6f7375c-46e3-11e3-96d1-99eafc7f081d.png)