Do a manual accessibility audit

[aciccarello]

I have #9 open for an automated test, but I should also do some manual auditing.

Some things I noticed with a quick test of VoiceOver.

• Reconsider use of links on images in image headers
• Reconsider lack of alt text in post list. Particularly for image posts it is significant
• Avoid separate links for image and post content (may require some theme re-writing depending on Remove Material Design #121)
• Photos page doesn't announce image alt text
• Should the tags list be labeled somehow?
• Add an accessibility policy to the website and request feedback