Allow Receipt of Wheel Events in MouseWheelNavigationInterceptor

Problem
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MouseWheelNavigationInterceptor is not receiving wheel events, so it cannot initiate navigation to the next item in the list. This is due to the automatic cancellation of such events when handled in EventSynthesizer.

Solution
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Fix by making the cancellation of wheel events configurable.

Unit Tests
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Tested the configuration option added to EventSynthesizer

How To +10/QA
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- Travis CI should pass.
- `grunt serve`
- Open ScrollList demo.
- Change to `single` scroll mode.
- _Should be able to use mouse to navigate among the items._

@lancefisher-wf @robbecker-wf @patkujawa-wf @georgelesica-wf @tomconnell-wf @todbachman-wf 

Attn: @robbielamb-wf 
`{boolean}`