Promo materials with slogan, website - showing support for OSM

[rskikuli]

During this edition of State of the Map I found it hard to (a) share the url of the website of the project (b) to explain in one sentence what CityZen does and (c) share the link of the GitHub repo where people can contribute to the project. I think this can be fixed partially by creating stickers featuring:

• the logo with the URL of the project;
• the logo with the slogan;
• the logo and the text 'get involved: git.cityzenapp.co' (we need to create the subdomain and redirect it to our GitHub repo.

Also in order to approach OSM contributors that might want to learn about the fact that they can contribute I propose to:

• create design for stickers that show something like "I edit OpenStreetMap through Cityzen;
• and to create design for stickers that show "CityZen <3 OpenStreetMap".