Adding default for container option

Added a default for container. Also removed the auto-appending of the element inside container. The calling plugin should be responsible for its own appending.

Status: **Ready to merge**

Reviewers: @kpeatt 

## Changes
- added default for `container`, defaulting to `$('<div />')`
- removed appending the element to the container

## How to test-drive this PR
- bower install this branch inside Pinny using the `append-to` branch
- `grunt serve`
- ensure Pinny is still working!