Umut,
I think there is a confusion in the terminology you use. What you see is starting up WSO2 application server cartridge instance. Infact there is nothing went wrong in your setup according to the logs.
Let me explain you what happens inside. When you start the setup, it will have the appserver cartridge xml deployed inside Cloud Controller. Since this is multitenant cartridge, it will create the appserver cluster at the start of the setup. So it spawns the cartridge instances using cartridge image(You have uploaded/ created in Openstack).
If you log into the Stratos controller dashboard, you can see appserver under multitenant cartridges and subscribe to it. Then you can access it using the url displayed. You can find user guide at[1].
[1] http://docs.wso2.org/display/Stratos200/GUI+User+Guide#GUIUserGuide-SubscribingtoaCartridge