Clean up throttle tests
Check false positives when testing the value of `this`
Fix issue #472

This commit fixes #472 by replacing cssreset/cssfonts
dependency with cssnormalize.
Update request module and node engine requirements
Remove path.existsSync as part of node 0.8 minimum environment
Add UA matching for IE 11+ and Opera 15+ (with Blink). Fixes #954 and #955

IE 11 introduces a new useragent that doesn't contain "MSIE", so we
sniff for "Trident" instead.

Opera 15 switches to the Blink engine and masquerades as Chrome and
Safari. We sniff for "OPR" to identify it as Opera, and also extract the
reported WebKit version (although this isn't really a real WebKit
version anymore, so at some point we should probably add sniffing
specifically for Blink).

Also refactored the UA test loop to be less goddamn cryptic.
Update history.
Update IO history
Update core history
Merge branch 'ua-ie-opera' of git://github.com/rgrove/yui3 into dev-master

Conflicts:
	src/yui/HISTORY.md
Build yui.
Merge pull request #913 from juandopazo/throttle-tests

Clean up throttle tests
Merge pull request #924 from tilomitra/cssgrids-dependency

Fix issue #472
Build YUI for merge of #924
Merge branch 'request-update' of git://github.com/clarle/yui3 into dev-master