upgrade express to 4.9.x

looking at the changes that caused the minor bumps in express, none are practical changes to the brisket api. the engine that createServer makes has a few more additional features but in a typical brisket powered app, those changes are more relevant to your top level express engine. for those reasons, im leaning much more to "patch level". i put it in quotes since the line is a little blurred while the project is < 1.0.0