Fix for -s option

[eraserhd]

For some reason, github won't let me issue a pull request from the topic branch today, but the our master is identical to the sdk_option_fix branch at the moment.

Prior to this patch, the -s option was used only to display an SDK name, and not to use one for running a project, as far as I can tell. This uses the selected SDK root. I have successfully used this to get iCuke to run apps under different simulator environments.

Thanks.s

(OK, it's acting weird - has just changed to topic request.)