Reference to NYC media assets

[cvee]

The base Change by Us code contains references to NYC media assets:

• Line 4063 of Change-By-Us/static/css/tc.gam.main.css
• Lines 481 and 496 of Change-By-Us/static/css/tc.gam.mobile.css

This causes CBU instances to display "Hey NYC!" on the main page.

[cybertoast]

The problem is primarily in naming convention. In both files there are a number of selectors whose names include "nyc" and a few image files whose names include "nyc". The solution is to remove the NYC reference in all cases so that only the image needs to be replaced for each city.
If there is city-specific content it should be included in an override file (tc.gam.overrides.css, for example) which is loaded after everything else. This also requires a code-change to load this custom overrides file after everything else.

For now the quick solution is to just change the image files themselves - ie make them custom for your city, but leave all filenames and references as they are.