a11y: webclient isn't accessible for screenreader users at all

[fcnjd]

As a blind user, who depends on a screenreader, I want to be able to use the Keybase interface. Currently, there are so much HTML standards that aren't kept, a link is not an element, things aren't labelled correctly and so on. For me this software isn't usable at all.

Criteria:

• HTML standards are kept
• All links, buttons and elements are clearly labelled
• Compliance with the WCAG 2.0 published by the W3 consortium