Container Div Style Application

[adamRenny]

Currently, the application relies on the user to produce a div with the proper styles (all child canvases are position: absolute; with top-left of 0, it is relative).

This should be moved to the JS engine where a user could choose to pass in a division similar to how THREE.JS performs its operations.

Use cases:

1. User provides a container div:
   • Layer applies position: relative; to the div
   • Layer checks for any child <canvas>es, applies position: absolute; top: 0; left: 0; to them
   • Continue workflow as normal
2. User provides non-container div:
   • Layer throws exception
3. User provides nothing:
   • Layer creates a properly styled div container and continues the workflow defined by case 1

[adamRenny]

This should be built after the jQuery Dependency Removal: #19

[aaronholsonege]

Ready for merge: https://github.com/adamRenny/LayerJS/tree/feature/%2352

[adamRenny]

5467fcf8f4b3abd9ba99770abe31be0ff37f65f5