Added before hook, fixed script test and canvas test.
Added before hook, fixed script test and canvas test.

 - Added a before hook to the <HEREMap> component tests, that loads the script and mounts a test map to the DOM.
 - Fixed the script test so instead of looking for an overall count of script elements (inaccurate), instead looking for a script element with the correct src for each script in the scriptMap.
 - Looked for the canvas element in the DOM that is created when the test map is rendered into the DOM and H.Map is called upon it.

Josh-ES/react-here-maps,Josh-ES/react-here-maps