Provide names.csv with the packge

[KonradUdoHannes]

The repository contains a names.csv file with reference data on the top level. It might be desirable to deliver this together with the source distribution inside the package. This could be done by the following steps.

• move the names.csv inside the package, for instance into a opencity/data/ folder
• inside the source code find the file relative to other source code files use __file__
• ensure that opencity/data/ (or just the .csv file in it) is included in the MANIFEST.in
• optional but recommended: add a test to opencity/tests/ that uses the included filedirection, i.e. that does not have a fallback to downloading the remote file. This way the CI will always check whether this file inclusion worked as well.