* Move ApiController to Api/BaseController

* API controllers inherit from Api::BaseController

* Add coverage for various error cases in api/base controller

Fix #2196 - Respond with 201 when Salmon accepted, 400 when unverified
Fix #2629 - Correctly handle confirm_domain? for local accounts
Unify rules for extracting author acct from XML, prefer <email>, fall back
to <name> + <uri> (see also #2017, #2172)

Since GNU Social hubs don't seem to return a hub.lease_seconds param in the subscription confirmation request,
we'll have to default that value to the GS "minimum" (from their code) which is 24 hours.

respect hub.lease_seconds (fix #46)