Add brand colour to organisations

Colours can now be picked for organisations independently of
anything else. This is similar to how organisations pick logos.

https://www.pivotaltracker.com/story/show/38409467
Add UK Trade & Investment colour
Reset Organisation column information

Also remove weird UTF-8 soft space thing.
Merge pull request #758 from alphagov/branding-colours-for-albs

Add brand colour to organisations

https://www.pivotaltracker.com/story/show/38409467