don't crash if ibrowse is already started

fix #COUCHDB-1986
diff --git a/test/04-replication-large-atts.t b/test/04-replication-large-atts.t
index 5386179..a7063c7 100755
--- a/test/04-replication-large-atts.t
+++ b/test/04-replication-large-atts.t
@@ -64,8 +64,8 @@
 
 test() ->
     couch_server_sup:start_link(test_util:config_files()),
-    ibrowse:start(),
-    crypto:start(),
+    application:start(ibrowse),
+    application:start(crypto),
     couch_config:set("attachments", "compressible_types", "text/*", false),
 
     Pairs = [