Switch to LCA2020

Remove LCA2018 and LCA2019 styles and content.
Add base LCA2020 styling and update references to year.

Make narrow-screen schedule details more distinct

In the narrow view, lots of details that aren't in the normal view
appear to compensate for not having clear row/column headers any more.

However, all the detail can look very same-same; this tweak makes rooms and end times more distinct.

Session chair info is made always italic, and a label is added to make
it clear that this person is not the speaker.

Improved menu styling

Update menu to use same style as static site,
with slight adjustments for Bootstrap 3.

Update fonts

Use the same fonts as the static site, as per the LCA2018 branding guide.
Shrink headings on the Dashboard to suit new fonts.

Improve display of abstract and presenter bio

Relocate buttons to be beside the presenter's name.

Format abstract and bio in monospace hack as intended.

Improve mobile view of schedule

Don't show the table header in mobile view

Style stripe payment form

It's rough but it at least outlines the box for credit card details

Use monospace font, hack, and not markdown.

Font should be made local and not remote loaded.

Use app.css not inlined css

Simpler for us.

Add ' *' required markers back

The bootstrap renderer did not do anything to signify required rows. We
can do this by adding a class for CSS to work on, and add this field in
a more simplified manner.

label-required == append ' *'