Extend webfinger capabilities.

lib/pleroma/web/web_finger/web_finger.ex

test/fixtures/httpoison_mock/atarifrosch_feed.xml

test/fixtures/httpoison_mock/atarifrosch_webfinger.xml

test/fixtures/httpoison_mock/eal_sakamoto.xml

test/fixtures/httpoison_mock/gs.example.org_host_meta

...s/httpoison_mock/https___pawoo.net_users_aqidaqidaqid.xml

test/fixtures/httpoison_mock/lain_squeet.me_webfinger.xml

test/fixtures/httpoison_mock/macgirvin.com_host_meta

test/fixtures/httpoison_mock/mamot.fr_host_meta

test/fixtures/httpoison_mock/mastodon.social_host_meta

test/fixtures/httpoison_mock/mastodon.xyz_host_meta

test/fixtures/httpoison_mock/pawoo.net_host_meta

test/fixtures/httpoison_mock/pleroma.soykaf.com_host_meta

test/fixtures/httpoison_mock/shitposter.club_host_meta

test/fixtures/httpoison_mock/social.heldscal.la_host_meta

test/fixtures/httpoison_mock/social.sakamoto.gq_host_meta

...poison_mock/social.stopwatchingus-heidelberg.de_host_meta

test/fixtures/httpoison_mock/social.wxcafe.net_host_meta

test/fixtures/httpoison_mock/squeet.me_host_meta

test/fixtures/nil_mention_entry.xml