Allow to rerun an audit on the report page

[krtek4]

It would be great to be able to rerun an audit of a particular page when displaying its report.

This will greatly speed up the fixing process :

1. Display the page report
2. Fix the error
3. Update the audit result

This will require to have some kind of "server" mode for a11ym where it keeps running after the audit is finished and awaits for update command.

Then we could send update request to this server using AJAX.

I envision something really simple, a small HTTP server listing on any port waiting for some JSON data sent via a POST request to tell a11ym which page to analyze and the needed options. No need to expose the whole CLI options, since this will probably be done on a per URL basis.

This is different than https://github.com/liip/TheA11yMachine/issues/11 and only targeted at local dev setups.

[Hywan]

So a11ymd? This is dangerous. We have to manage tokens to limit number of requests per user in time for instance. Thoughts?

[krtek4]

@Hywan I tried to explain better what I mean in the issue. The goal is not to listen to the whole world, just command from the same machine where the "server" runs. The idea is only to speed up accessibility issues fixing, not allowing other people to launch jobs.