Added assertion for incorrect container lookup names
Merge pull request #2769 from sebastianseilund/normalize-assertion

Added assertion for incorrect container lookup names
Fix assertion, arguments.length should be less than 2
Fix typo
Merge pull request #2778 from bradfol/action-docs

Action helper docs
Merge pull request #2777 from bradfol/handlebars-helper-assert

Fix assertion for Ember.Handlebars.helper
Tests clearRenderedChildren against metamorphViews children
Adds a test to metamorph_view_test.js for detecting if metamorphViews are being deleted by their parents or not when parent.clearRenderedChildren() is called
Issue #2572