domain-util: Fix checkDomain, so it checks all error codes. (#370)
domain-util: Fix checkDomain, so it checks all error codes. (#370)

This fixes an issue where if server send non 404 error code such
as 403 forbidden we marked them as Zulip server even though they are
not, now it checks for 400 error range.
zulip/zulip-electron,zulip/zulip-desktop,zulip/zulip-desktop,zulip/zulip-desktop,zulip/zulip-electron,zulip/zulip-desktop,zulip/zulip-electron