Added jQuery approach to enable local HTTP requests with JavaScript.

Browsers usually return HTTP status 0 for requests using a local protocol like file, app...
For local development it's nice to use simulated HTTP status 200 or 404 if responseText ist available or not (jQuery does exactly that and I implemented that solution).
Removed empty line
Merge pull request #3353 from derRaab/development

Added jQuery approach to enabled local HTTP requests with JavaScript