Add support for swiping left/right to close/open mobile nav.

Adds a custom build of jQuery mobile that ONLY includes the necessary
modules for swipe events.
Prevent content scrolling in mobile browsers when nav open.
Merge pull request #578 from ericras/develop

Notices
Merge pull request #580 from kabel/swipe-nav

Swipe open/close mobile navigation
Clarify less breakpoint description
Merge pull request #582 from skoolbus39/develop

Clarify less breakpoint description, test pull request from Ryan
Notices: Implement .overlay-header and .overlay-maincontent instead of .float
Merge branch 'floating-notices' of github.com:ericras/wdntemplates into floating-notices

Conflicts:
	wdn/templates_4.0/examples/notice.html
	wdn/templates_4.0/less/modules/notices.less
	wdn/templates_4.0/scripts/notice.js