Add app promo to all pages

Use SSI
enable SSI on vagrant
we should be refactoring more code

Conflicts:
	.htaccess
Added Sponsors Registration page
Adjusted the registration page for Virtual Attendance only
- Adjusted the why-attend page's call to action at the bottom
- Made sure the registration page removes the iframe on touch devices and narrow screens
- Adjusted the Sponsor's Registration link on the home page