Fixes accept header not sent via GET request

[vedmaka]

• Accept header for the GET curl request was sent as an Accept URL parameter rather than a header, fixed by adding $arrayHeader param to the fetchUrl method of the Curl class
• Adds format URL parameter to GET requests to support AWS Neptune

[BorderCloud]

Thanks for the pull request for Neptune. The support of Accept, idem for format, are different between the databases in the past. I need to check in the previous databases, before validating this Pull request. Thanks !