Feature request: Add X-BrowserSync-* headers to all HTTP responses

[enspritz]

Issue details

As in title. This will help to identify request/response flow in more complicated setups.
Use case here is multiple BrowserSync instances fronted by Envoy Proxy with non-trivial routing setup; these headers will help narrow down where trouble is originating.

Might be a matter of adding a default middleware whose handler adds the headers:

res.setHeader('X-BrowserSync-URL',     'http://localhost:8080'); // The value of the actual local access URL
res.setHeader('X-BrowserSync-Version', '3.0.3');

Please specify which version of Browsersync, node and npm you're running

• Browsersync [ 3.0.3 ]