Update title of apps guidance
First pass at converting slide deck into guidance
Merge branch 'master' into standalone-apps

Conflicts:
	service-manual/making-software/standalone-apps.md
Add further reading links
Add exceptions content
Replace ampersands with 'and'
Update 'web app' guidance

Change to responsive web design as per Ade's suggestion

Update examples with links, remove Virgin Active as can't find live link
Merge pull request #74 from alphagov/standalone-apps

Standalone apps guidance