fix(test): add consistency about named spy

Use this.showSpy for `expect(this.showSpy)` instead of
`expect(this.myRegion.onShow)`.

Just doing the same thing as this.swapSpy.
feat(region): pass the option to the trigger events

 * pass view, region, options to any triggers
 * add test for region show triggers
 * add documentation about new arguments for region show events
Merge pull request #2066 from stephanebachelier/region-trigger-options

Region triggerMethod options