Fix typo: sectionAction -> sendAction
Merge pull request #4786 from radar/section-action-typo

Fix typo: sectionAction -> sendAction
Clarify test-run instructions

`es6-module-transpiler` is needed to run the tests, so an `npm install` is needed. Furthermore, users using zsh will have issues with the brackets inside the test command and will need to escape the test command lest they receive the `zsh: no matches found: test[all]` error.
Merge pull request #4788 from robyurkowski/patch-1

Clarify test-run instructions
Implemented a per-property sort order in Sortable mixin