Improve Web Accessibility

[gtirloni]

While suggesting the use of Mattermost as a replacement for Slack/IRC, it was mentioned to me that it would pose a problem for our target audience due to some accessibility issues. Right now, Slack isn't very great in that area either.

I'm opening this issue so the WCAG 2.0 guidelines may be considered in the future.

[mattermod]

Thanks @gtirloni, appreciate your feedback,

To keep feature idea discussions in one place, could we have your help:

1. Contributing this in the feature idea forum so it can be discussed, upvoted and considered for a ticket accepting pull requests?

   Please include a link back to this GitHub Issue. If you're interested in implementing, please say so and we'll prioritize the review.

2. Posting a link back from the feature idea forum to this thread?

[gtirloni]

Link to feature idea forum: https://mattermost.uservoice.com/forums/306457-general/suggestions/13036146-improve-web-accessibility