This was removed from the diaspora_federation gem, since it's not used
for the federation/discovery anymore since a long time. But old versions
of the ConnectionTester up to version 0.7.17 still check if this route
exist or else they mark the pod as offline. So lets add a dummy
host-meta with an empty response back, so the ConnectionTester is happy
again until we can remove this workaround again.
Remove partial support for CORS on webfinger routes and replace
it with the Rack::Cors middleware. This provides more complete
CORS support and works around a caching issue with nginx on
Heroku and potentially other reverse proxies.
CORS headers are only added if the incoming request includes
an "Origin" header, which seems to be correct according to
the CORS spec.
closes#2216
