Hybrid projects

# Including CSS best practices for Hybrid App projects

Status: **Up For Review**

Reviewers: @kpeatt @rosshojo @jeffkamo @mobifydave @jansepar 
JIRA: https://mobify.atlassian.net/browse/GOLD-1164

## Changes
- Initialized new page in the css code styles and filled in what we currently have established as best practices.
This directory structure makes broad sense to me. We may want to call the directories app-{platform}, e.g. app-android so they group in lists, but that’s a nit.

Whether or not to go with a single app stylesheet or do separate ones for each app probably revolves around maintenance and business expectations. Since we’re selling consistency across web and apps as a key benefit and differentiator, clients probably shouldn’t expect to be able to have radically different builds across native platforms… So that leads me to think that a single directory for app styles /might/ be the way to go, at least as a default. If clients expect more than a few teaks between apps, then separate stylesheets per app makes more sense, trading off code isolation against additional maintenance.