Initial version of tip carousel

@lauraxt r?

Bit tricky to test.

1) Just load the page and nothing weird or new should happen.
2) Duplicate the list item under  <ul id="carousel"> and then load up the page again.

With number 2, the tips should cycle through the two tips at a rate of 5 seconds per tip.

This is the simple version 1,we can work from here to add features etc. if need be.