Remove render blocking resources from web proxy

[amoeba]

The HTML template the web proxy uses puts two render-blocking resources in the head tag. I noticed this because loading the page is noticeably slow. We should move these down into the end of the body so they don't render-block.

slinky/deploy/docker/web/templates/base.html

Lines 6 to 9 in 102941f

	<link href="https://api.test.dataone.org/slinky/static/css/base.css" rel="stylesheet">
	<link href="https://api.test.dataone.org/slinky/static/css/index.css" rel="stylesheet">
	<link href="https://unpkg.com/@triply/yasgui/build/yasgui.min.css" rel="stylesheet" type="text/css" />
	<script src="https://unpkg.com/@triply/yasgui/build/yasgui.min.js"></script>

While we're at it, there are a few more things we should change. Here's the full list:

• Move render-blocking resources out of the head tag
• Serve all resources our own origin rather than unpkg
• Don't hard-code the location of any resources, instead load resources from the appropriate location regardless of deployment context

I might make some style/layout tweaks while I'm in here too.