More styling and JS chnages for DCC theme

- Added Bootstrap ScrollSpy library to handle 2nd main nav
- Deleted function.js since ScrollSpy will be used
- Moved div closing tag to encapsulate entire 2nd main nav
- Applied styling to .second-main-nav to handle fly-in on scroll
- Sorted out the width of the second main nav
- Changed the top margin of main content
- Sorted out positioning of the mini-bumblehornet