major refactor for express-yui@1.0.0

this version is not compatible with previous version of the plugin.

Notes

• the plugin is now a class definition that can be extended easily.
• leverage Y.Template.register() and Y.Template.get(), available in yui 3.12.x.
• a compiled version of the template is provisioned under the bundle object for runtime on the server side.
• yui output format is now opt-in.
• example does not use express-yui anymore, instead it uses express-view.
• the micro component can be controlled from outside by providing a custom version of it when creating an instance of the plugin.

relaxing yui dependency

From now on, the yui version installed at the top level of the application is going to be the one dictating what version should be used by the dependencies.