Handle WAInvalidUrlSyntaxError in WAServerAdaptor #contextFor:

[GoogleCodeExporter]

WAServerAdaptor >> #contextFor: may signal a WAInvalidUrlSyntaxError in the 
rare case when the request URL is invalid. It would be nice if the could return 
an HTTP 400 in that case.

The way it looks to me the methods would have to be refactored a bit to make it 
not too messy.

Original issue reported on code.google.com by philippe...@gmail.com on 8 Sep 2013 at 9:23