sets up $.observeDOM so that functions can be run on event

This replaces the targeted call for the nav.  This will also only listen
for changes lower then the element targeted so we don't get it called
all that much
provide a smooth transition from one min-height to another

this change keeps the main min-height as low as possible and ensures
that we are not creating any jarring content move.
suggested change for 153#issuecomment-61721726
we should include the margins just incase that was altered
Merge pull request #156 from washingtonstateuniversity/bug-scroll

[PR] Clean up and refactor of fix for #150