Give "create" transactions a readable type in "transaction.search"

Summary:
Ref T13151. See PHI725. By default, "transaction.search" doesn't provide details about transactions because many have bad/weird/policy-violating internal types or fields.

The "create" transaction is simple and straightforward, so label it to allow callers to distinguish it.

Test Plan:
  - Created a new task.
  - Called `transaction.search` on it.
  - Saw the labelled "create" transaction.

Reviewers: amckinley

Reviewed By: amckinley

Subscribers: swisspol

Maniphest Tasks: T13151

Differential Revision: https://secure.phabricator.com/D19505

src/applications/transactions/conduit/TransactionSearchConduitAPIMethod.php

@@ -205,6 +205,9 @@ final class TransactionSearchConduitAPIMethod
           case PhabricatorTransactions::TYPE_COMMENT:
             $type = 'comment';
             break;
+          case PhabricatorTransactions::TYPE_CREATE:
+            $type = 'create';
+            break;
         }
       }