delete-empty-repos.sh - Handle Pagination

[delete-empty-repos.sh](https://github.com/github/platform-samples/blob/master/api/bash/delete-empty-repos.sh) currently works with default pagination of only 30 repositories.

Need to handle pagination in case of more than 30 repositories are within the organization.

[Relevant Doc](https://developer.github.com/v3/guides/traversing-with-pagination/)

Read api/bash/delete-empty-repos.sh and the linked GitHub pagination guide first. Run it against an organization with more than 30 repositories, then verify that it processes all repositories rather than only the default page.

Written by the indexing model from the issue text.