Refactor Custom Styling

[AustinCarr]

Refactored how the custom styling for the SVG works, it will no longer create style tags, but instead add in-line styles to the SVG paths.

Renames "dynamic-map-css" to "dynamic-map-helpers" since it only has helper functions in it now, and the dynamic CSS is done in the Map component.

Deletes tests for removed code. Adds tests for helper functions.

Updated README.

[dd-han]

I feel it useful for application which need multiple instance