Evaluate Font Awesome usage

[carrythebanner]

The front end theme uses Font Awesome, but only in a few places. If our usage is minimal and can be replaced with a few custom icons, we could consider dropping it as a dependency.

If we do want to keep it, note that we're using an old, unmaintained version (v4.7.0; see https://fontawesome.com/versions). I'm not aware of anything particularly problematic about using an old icon library, but worth looking at the newer versions to see what they offer.

[ionous]

i think this is the extent of font-awesome usage:
https://github.com/search?q=repo%3Ashift-org%2Fshift-docs+%22fa+%22&type=code

• theme.css: not applicable if not used
• readme: just documentation
• front.js: for owlCarousel buttons, but it looks like even though the code specifies icons; it explicitly hides them.
• 404.html layout: but actually the site only uses that in local development, netlify copies a different 404 page over top of it.
• nav.html partial - the "hamburger" menu when for narrow pages ( ex. on mobile )
• list.html layout -- but the site doesn't actually those listing pages ( ex https://www.shift2bikes.org/archive/ )

so, tentatively, just the menu icon is used:

we could use <span class="glyphicon glyphicon-align-justify" ></span> from bootstrap3 (which is already included) as a close replacement ( maybe adding an additional class to tweak the span's margin, etc. to match what's in theme.css )