add offset & for loop to get all submissions

[fennellkyle]

#1
Added offset to the http request.
Setup a while loop that breaks if the response object has less than limit, indicating that this is the last loop.

[hRun]

Quick heads-up: Sorry for the long waiting time, that's usually not my style. I didn't forget about your pull request but was unable to test so far due to delays in getting access to a Bugcrowd program's API.