Switch order of stacks on GOV.UK as requested

Signed off by Mr H. H.
Lint visitors-realtime.js
Add GDS/UK specific datetime config

There are a couple of differences from standard Moment here:

- LT: instead of '8:30 PM' we render '8:30pm'
- L: instead of '03/24/2013' we render '24 Mar 2013'
Change display of labels on realtime sparkline

- Remove right hand label on hover
- Bring relative time onto separate line