Hide WordPress Admin bar margin from non-users.

Without this, WordPress adds a 28px top-margin to the HTML element of
the page, which is noticeable because we use the background image on
HTML and BODY to work-around browsers without multiple background-image
support.
Quick fixes.

Added Google Analytics code ID. Added Title to the jumbotron. Removed
duplicate call to wp_head() in index.php. Fixed spelling error in
page.php.