adding support for custom filter and combine when generating seed urls
adding expyui.debug() middleware
adding example of how to use the custom debug mode
updating docs, reprecating app.yui.debugMode() in favor of the middleware
adding history entry for 0.5.8
removing debugMode() now that it is deprecated
Merge pull request #21 from caridy/custom-seed-config

* adding `debug` middleware to control it per request
* making `expose` middleware connect/express compatible.