(Bug 5073) New account links layout for Foundation

* Splits up the way the account links area renders
  for the old Tropo and new Foundation layout
* Turns logging in into a modal
(Bug 5073) Further progress on Foundation masthead

* Modal now activated by clicking username on left side
  of menu bar
* Small icon version in masthead on small screens
* No icon in modal
* Smaller text for quick links so they are not as overwhelming
  and don't overlap with logo on medium screens
(Bug 5073) Don't replicate account link HTML

Figured out a way to make the account link text into
a modal without replicating the account link. This involved
applying the reveal CSS to the account-link-text ID ONLY
when the screen is small.  Additionally, add a close reveal
link that is hidden when the page is medium/above.

The ONE problem this has is very small:

When resizing the screen to small, activating the modal, closing
the modal, then resizing the screen to large, the account
links do not appear again.  However, this is a very small
problem that probably will not be too hard to fix if necessary.
(Bug 5073) account link access link always unvisited link color
(Bug 5073) Reveal CSS needs to be available
(Bug 5073) Redefine row width for Foundation

Back when tropo was .9em the page width was set to 80em.
However, translated to 1em that mean 64em wide instead.
(Bug 5073) Finesse login links and buttons

* On mobile, put login link in menu bar
* On desktop, login link is button in masthead
* For link buttons, retain the primary text color
* For secondary link buttons, retain text color
* Add primary-text-color for lynx
* For login form, realign columns
Merge pull request #623 from foxfirefey/accountlinks

Responsive masthead