issue #264, converted ask and wait to block to expression from step

I'm not exactly sure what was meant by "this is broken", but it seems to me that this block is much more useful as an expression ala:

![screen shot 2013-09-24 at 9 26 56 pm](https://f.cloud.github.com/assets/5093064/1205890/b7fc0c8e-2592-11e3-9bb6-e879ca90d60e.png)