stop using paper-styles classes

[notwaldorf]

Removes any use of the /deep/ flex classes.

This is the most important and also most annoying element, since a) it literally substitute class names and b) it's used in iron-component-page and therefore in every single page of the catalog 😹:gun:

I've also explicitly called out iron-flex-layout in bower.json, even though it's included in paper-styles. I don't know, too pedantic?

[addyosmani]

LGTM, but there may be more nuance around the approach that I'm missing. Deferring to grand master @cdata.

[blasten]

@notwaldorf awesome, lgtm! Thanks for working on this on a sun 😸🎉