Adding default for container option

Removed the auto-appending of the element inside container. The calling plugin should be responsible for its own appending. Also adding a locked decorator class to indicate when lockup is locked. 

Status: **Ready to merge**

Reviewers: @kpeatt 
JIRA: https://mobify.atlassian.net/browse/CSOPS-921
Linked PRs: https://github.com/mobify/pinny/pull/56

## Changes
- removed appending the element to the container
- added `LOCKED` class when lockup is locked.

## How to test-drive this PR
- bower install this branch inside Pinny using the `append-to` branch
- `grunt serve`
- ensure Pinny is still working!

This is basically just the above logic simplified.