House Styles Bundle

[sarahsnow1]

Overview

Creates a resource bundle for all of the house styles and loads stylesheets through it. Resolves stylesheets missing resources as well as loading issues for third party apps.

Proposed Changes

• Updates stylesheet submodule locations to programmatic bundle (creates folder references for each stylesheet so resources are loaded dynamically)
• Removes stylesheet resource build phases, dynamically loads stylesheet dependencies
• Creates bundle extensions for accessing the mapzen sdk bundle as well as the stylesheet bundle (the SDK bundle will hold all images and any future xibs)

Closes #225

[msmollin]

LGTM. I tested this by loading the pod into a harness project, with my existing SDK repo, and with a fresh clone. All appear to work correctly.