Church Online banner on watch area height

Set the church online banner on Watch page to change height depending on
screen height, to make sure On Demand content is always peeking into
view.

Changes to be committed:
modified:   scss/pages/_watch.scss
modified:   stylesheets/app.css
modified:   watch/index.html
Merge branch 'master' of github.com:lifechurch/lifechurch-site