Add Y.require() support to client shim
Add Y.require() support to server-side shim

Closes #50
Keep app.yui.use chainable on the client-side shim
Update YUI mocks to expose `Y.require()` mock
update docs for 1.3.0 after PR #51
bumping 1.3.0 after PR #51, adding history entry
better error control when dealing with ready state and errors in the callback
adding tests for PR #54, improve async tests using ypromise
making jshint happy, I guess we will not be able to fully use the nice syntax new Promise().catch() feature after all
preveting callback to be called twice when it fails the first time
preventing callback to be executed twice when ready is rejected
doing the right thing for Promise polyfill
history entry and bump version for 1.3.1 from PR #54
docs for v1.3.1
supporting multiple calls to use() and ready()
bumping for version 1.3.2
Merge branch 'bootstrap' of https://github.com/caridy/express-yui
docs for version 1.3.2