Remove duplicate meta viewport tag

* Keep topmost viewport tag, remove decimal point from initial-scale
Use local HTML5 shiv

* Remove external CDN version
* Remove duplicate which was linking to external assets
* Use the latest version, 3.7.0
Use local favicon

* Add favicon to image assets
* Remove external references to app icons and og:image
Remove uses of New Transport

* Remove links to external font files and IE fallbacks
* Default headers to Helvetica (bootstrap default)
* Apply Gill Sans to the nav bar and tweak spacing
* This brings transition app inline with other admin apps, and holds
off on any potential migration to using new transport in the future.
Merge pull request #40 from alphagov/use-local-assets

Use local assets over external ones [58158124]