Replaces legacy API URL, encode post request in json and parse response for result. Fixes #1474

[varuuntiwari]

Tested the JSON request by printing out the generated body and running on Postman, giving accurate responses back from API. However, some points are left:

• An issue remains, which is testing it as a NSE script since the Nmap distribution installed in my system fails to support SSL somehow.
• The API only accepts HTTPS connections even though the URL is given as http;//, which makes it tricky to test it without removing nmap and fixing the issue with SSL in my system.

The SSL problem is related to a single system, so I have pushed this branch in confidence that it works based on external tests. In the meantime, this commit is expected to fix the issue or even help others working on the same issue.