Fix undeclared `http` variable for Node.js
Fix undeclared `http` variable for Node.js

In commit 3f129bbcc1025be786da34216ba40c05ad495eea,
where the http files were restructured, it looks like the `import http`
was not added to the new file.

This causes a 'ReferenceError: http is not defined' when trying to
get a geotiff.

I've removed the `if (http.get)`, since normally, it should never fail.
If we are running on a browser, fetch() should exist for any new browser,
otherwise XMLHttpRequest would exist.

Therefore, we must be running on Node.JS, where the http library exists.

constantinius/geotiff.js,constantinius/geotiff.js,constantinius/geotiff.js