Use URL fragments for #tide-{windows,levels}

This allows us to treat the two views as "pages".

It also gives the user the ability to bookmark and link to a particular
page.
Track the tide levels/windows tabs as pageviews

https://www.pivotaltracker.com/story/show/75115658
[Delivers #75115658]
Merge pull request #13 from sealevelresearch/track-tab-page-views

Track the tide levels/windows tabs as pageviews