Add Various U.S. government GitHub orgs to the list

[jordangov]

Thanks for the contribution! Below is a template that can make it easier when submitting your Organization:

NOTE: This PR adds numerous organizations from within the Department of Homeland Security as well as a few others that can be found on code.gov (the US code metadata repository). If we need to only include DHS organizations I can modify the PR, but since these are publicly known via code.gov I think they should be good to include.

Your Organization: Department of Homeland Security
GitHub Organization url: @dhs-gov
Country/Locality: United States

Inclusion requirements:

• Referenced account is an Organization not a User^
• If this is a government project, your Organization's description should include a reference to your country/agency.
• Make sure your Organization includes at least one public repository
• Please also include a URL for your organization that links back to your organization or agency homepage.

^ If you want to convert your account to an org, details can be found here: https://help.github.com/articles/converting-a-user-into-an-organization/

❤️ GitHub Government Contributors