Fix IE11 detection in BrowserInfo.js

**ULTIMATE PROBLEM**
Since Microsoft removed the MSIE token from the IE11 UA string, BrowserInfo was unable to identify IE11 and was falling back to webkit. This was causing problems for determining whether to use `mousewheel` or `wheel` events.

**SOLUTION**
If a browser isn't identified on the first pass, the UA string is checked for the `Trident` token, which is a part of the IE UA string from IE9 and up. (See [here](http://msdn.microsoft.com/en-us/library/ms537503(v=vs.85).aspx#TriToken) for info)

**TESTING SUGGESTIONS**
In an IE11 VM, verify that `BrowserInfo.detectBrowser` will return IE.

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Please review: @timmccall-wf @trentgrover-wf