Pleroma, Akkoma, and other servers do not follow the Mastodon spec
for the 'uri' attribute which specifies that it contains the domain
name of the instance. Instead, they return a complete URI.
As a workaround, we now detect this situation and parse out the
domain from the URI when necessary. This fixes issue #347.
Thanks to @laleanor for their patch and @rjp for ideas on how to
make it work with GotoSocial and other servers