main top nav: move from landing.html to layout.html

Move the main navigation into the layout file to make it visible on all
pages.
main top nav: add new page links

Links to:

* Enter Event Code
* View Points
* View Upcoming Events

Comment out the Orders page link for now.
main top nav: make navbar responsive

Add some Bootstrap classes to make the navigation bar responsive. Hides
the navigation when the document width becomes too small. Adds a
hamburger menu to show & hide the nav links.
main top nav: change "View Points" to "View Your Points"

Makes it clearer. If you think "View My Points" is better, go ahead.
Merge pull request #8 from drenfr01/feature/global-mobile-friendly-navbar

Feature/global mobile friendly navbar