Add U.S. Geological Survey (USGS) to Agencies List

[RicardoAReyes]

U.S. Geological Survey (USGS) is working on their code.json file and it should be ready for harvesting in 2 weeks.

DoI has not prioritize the implementation of the agency's code.json file. And for that reason USGS would like to be listed separately on Code.gov, similar to NSA.

Expected Behavior

Add USGS under agencies list.
https://www.code.gov/#/explore-code/agencies/NSA

Add record to
https://github.com/GSA/code-gov-web/blob/master/src/assets/agencies.json

[DanielJDufour]

@froi , I think this is another backend task. Thanks for the heads up @RicardoAReyes !