Added links and images to two new prototypes.

One shows ambassador Twitter networks and the other attempt at GOV.UK anomaly setection
Merge pull request #617 from alphagov/feature/FCO_Traffic_Prototypes

Added links and images to two new prototypes.
Amend text on visit visa dashboard

Story: https://www.pivotaltracker.com/story/show/74205142
Merge pull request #623 from alphagov/bugfix/text-change-for-visit-visas

Amend text on visit visa dashboard