-make econtract optional as per design

src/exchange/taler-exchange-httpd_purses_create.c

@@ -135,6 +135,12 @@ struct PurseCreateContext
    * Minimum age for deposits into this purse.
    */
   uint32_t min_age;
+
+  /**
+   * Do we have an @e econtract?
+   */
+  bool no_econtract;
+
 };
 
 
@@ -370,6 +376,8 @@ create_transaction (void *cls,
     }
   }
   /* 3) if present, persist contract */
+  if (! pcc->no_econtract)
+  {
     in_conflict = true;
     qs = TEH_plugin->insert_contract (TEH_plugin->cls,
                                       pcc->purse_pub,
@@ -426,6 +434,7 @@ create_transaction (void *cls,
       GNUNET_free (econtract.econtract);
       return GNUNET_DB_STATUS_HARD_ERROR;
     }
+  }
   return qs;
 }
 
@@ -664,7 +673,6 @@ TEH_handler_purses_create (
   json_t *deposits;
   json_t *deposit;
   unsigned int idx;
-  bool no_econtract = true;
   struct GNUNET_JSON_Specification spec[] = {
     TALER_JSON_spec_amount ("amount",
                             TEH_currency,
@@ -674,7 +682,7 @@ TEH_handler_purses_create (
     GNUNET_JSON_spec_mark_optional (
       TALER_JSON_spec_econtract ("econtract",
                                  &pcc.econtract),
-      &no_econtract),
+      &pcc.no_econtract),
     GNUNET_JSON_spec_fixed_auto ("merge_pub",
                                  &pcc.merge_pub),
     GNUNET_JSON_spec_fixed_auto ("purse_sig",
@@ -815,7 +823,7 @@ TEH_handler_purses_create (
                                        TALER_EC_EXCHANGE_PURSE_CREATE_SIGNATURE_INVALID,
                                        NULL);
   }
-  if ( (! no_econtract) &&
+  if ( (! pcc.no_econtract) &&
        (GNUNET_OK !=
         TALER_wallet_econtract_upload_verify (pcc.econtract.econtract,
                                               pcc.econtract.econtract_size,