Display logged in username at top of the page.

Besides the logged in user's name, this includes a dropdown menu with options for logout (functioning) and settings (a placeholder that we can always comment-out).

I was playing with bootstrap customisation and fonts to give deploystream a more distinctive look, and I cheekily included these in the PR. Let me know how you like the new fonts - we can always revert to the standard helveticas if you don't like these...