Fix Amazon Silk detection in Y.UA.

Amazon updated the UA string as specified here:
http://docs.aws.amazon.com/silk/latest/developerguide/user-agent.html
Build yui.
Update yui history.
Merge branch 'dev-master' into dev-3.x

Conflicts:
	build/yui-base/yui-base-coverage.js
	build/yui-base/yui-base-min.js
	build/yui-core/yui-core-coverage.js
	build/yui-core/yui-core-min.js
	build/yui-nodejs/yui-nodejs-coverage.js
	build/yui-nodejs/yui-nodejs-min.js
	build/yui/yui-coverage.js
	build/yui/yui-min.js