Remove redundant truthy check for properties of icons in index.js
We test if all icon scan be retrieved anyway, if any icon is missing these properties we would find out during testing.
* Refactor prepublish script to use template file for icon objects
... to hopefully increase readability
* Fix build and test issues
* Add missing semi-colon
* Explicitly check for errors when writing individual static .js files
* Add URL friendy/slug/file name as property to package icon objects
* Test new property
* Build index from template
* Add .get function to index.js export
* Test new .get function in index.js export
* Use Uglify-JS to minify the code in the package's index.js
* Update API in README.md
* Renaem test using "slug" instead of "name"
