Added Keystone 3002

Hi, I've added the Keystone 3002 battery holder for 2032 button cells.

Documentation sources:

• https://www.tme.eu/it/Document/a823211ec201a9e209042d155fe22d2b/KEYS2996.pdf
• https://www.mouser.it/Power/Battery-Holders-Clips-Contacts/Coin-Cell-Battery-Holders/Datasheets/_/N-cicxg?keyword=534-3002
• https://www.mouser.it/datasheet/2/209/epd_10012015_12BH002-GR-1171043.pdf (clone)

Updated to 14fe1eda

---

Thanks for creating a pull request to contribute to the KiCad libraries! To speed up integration of your PR, please check the following items:

• Provide a URL to a datasheet for the footprint(s) you are contributing
• An example screenshot image is very helpful
• If there are matching symbol or 3D model pull requests, provide link(s) as appropriate
• Check the output of the Travis automated check scripts - fix any errors as required