Allow use of `el` in RegionManager.addRegion definition.

Throw error if impropper configuration passed to RegionManager.addRegion.
Merge pull request #1774 from jaridmargolin/master

Allow use of `el` in RegionManager.addRegion definition.
s/appliction/application/
Merge pull request #1776 from moimikey/mh/jsdoc-application-hotfix

typo in application.jsdoc
Alter Marionette.normalizeUIKeys to return a new/non-mutated hash
Merge branch 'minor' of https://github.com/marionettejs/backbone.marionette into feature/issue_1728