Fixed whitespace before navbar items

Meant for the message board portlet because the portlet title and navbar
were overlapping. Rules also added to override this new margin for the
dockbar and the site-navigation menus so their appearance is not affected.
Navigaiton background changes onscroll (980px max-width)

Bugfix: this rule was added earlier, but nested incorrectly so it did not
actually work. Now it darkens in color as the page is scrolled down like
the other dockbar/navigation elements
Fixed toggle option for Carousel controls

The code previously did not work -- the controls were always hidden no
matter the input from the checkbox. Now, they are able to be toggled on
and off properly. Also, they are aligned left instead of right so that
they are not cut off on resizing the window.
Created Jumbotron structure, template and example article

Previously, the first portlet in the hompage column 1 would receive this
styling, but this selector caused a lot of problems. For example, the
admin features and maximized view got the styling, and it didn't look as
intended with different layouts. Now, it is restricted to the .jumbotron
class, which is added dynamically when the jumbotron structure is used.
Update site template

* Include new jumbotron example
* Move pagination example to Media page
* Removed deleted web content from assets.json