input type="file" styling

file inputs are wacky and hate to be styled, and although I would generally lean toward NOT styling them, I am adding this issue because there is a bug filed for it.

Bug:
- https://bugz.meetup.com/show_bug.cgi?id=37161

Resources:
- http://stackoverflow.com/questions/572768/styling-an-input-type-file-button
- http://ericbidelman.tumblr.com/post/14636214755/making-file-inputs-a-pleasure-to-look-at
- http://css-tricks.com/snippets/css/custom-file-input-styling-webkitblink/

If we make a plan here about whether we want to tackle this issue, we can update the bug accordingly.