Should update windows PATH

[neils-s]

The package installer should have an option to automatically update the windows environment variables. For example, the 'bin' subdirectory of the Neo4j installation directory (e.g. "C:\tools\Neo4j community\Neo4j community 3.5.1\bin") should probably be added to the windows PATH environment variable automatically.

Apparently, the NEO4J_PATH environment variable with the path to the most recent Neo4j installation is set, so this can be used as a shim to update the windows PATH. However, I couldn't find this behavior documented, so I don't know if the NEO4J_PATH environment variable will be robust in the future.