In order to test GH integration, there should be a script able to send requests like the ones sent by GH when a PR is created or modified or when a PR/commit message mentions bpo-NNNNN.

The script should be able to:

1. read and send payloads from a file
2. generate payloads of the given type, with the values provided or with default values.

This script might also be exploited by the tests.