From Arcanist, send 'host' to server for validation on setup workflows

Summary: This allows us to detect and complain about mismatched client and
server host identities. It causes some subtle and not-so-subtle problems if the
client and server don't agree on the install's primary URI.
Test Plan: Ran "arc install-certificate" and "arc list" against my local host
with intentionally bogus configs and was warned. Ran with normal configs and
everything worked.
Reviewed By: tuomaspelkonen
Reviewers: jungejason, llorca, tuomaspelkonen, aran
CC: aran, tuomaspelkonen
Differential Revision: 591

scripts/arcanist.php

@@ -244,6 +244,7 @@ try {
           'clientDescription' => php_uname('n').':'.$description,
           'user'              => $user_name,
           'certificate'       => $certificate,
+          'host'              => $conduit_uri,
         ));
     } catch (ConduitClientException $ex) {
       if ($ex->getErrorCode() == 'ERR-NO-CERTIFICATE' ||

src/workflow/install-certificate/ArcanistInstallCertificateWorkflow.php

@@ -101,6 +101,7 @@ EOTEXT
       'conduit.getcertificate',
       array(
         'token' => $token,
+        'host'  => $uri,
       ));
 
     $user = $info['username'];