Make `host` optional for `oci` database resources

`oci` uses Zend's `Oracle` adapter, which does not use this setting at
all.

application/forms/Config/Resource/DbResourceForm.php

@@ -58,7 +58,7 @@ class DbResourceForm extends Form
             $offerMysql = true;
         }
 
-        if ($dbChoice === 'oracle') {
+        if ($dbChoice === 'oracle' || $dbChoice === 'oci') {
             $hostIsRequired = false;
         } else {
             $hostIsRequired = true;