Remove documentation about View.serializeData

The Marionette.View does not have this method.
Add documentation of serializeModel
Fix broken Documentation Index link for childview

Fix the Documentation Index link for "childview:*" event bubbling from child views.
Cleanup typos across docs and changelog.
Documentation fix: broken link to Marionette.View

Fix link to point to marionette.view.html rather than marionette.view.md.
Passes model and index to emptyViewOptions.
Fix testcase typo
Fix wrong variable usage in removeRegion
Replace region innerHTML with jquery html.

Fixes #2027