Thursday + Takeflight changes (#31)

* Adds Facebook svg button, and adds Facebook link type to models

* CSS work from takeflight, 30 June 2016

* Adds drop-down menus for navigation

* Adds mobile menus for navigation

* Minor tweak to mobile nav headings

* Makes the logo a link back to the homepage

* Updates the footer to the current version, removing sponsor logos for the moment.