ConnectionStrings.config should be machine agnostic

[dsolovay]

The ConnectionStrings.config file contains environment specific information. It should be renamed to ConnectionStrings.config.example, and a step should be added to the README to rename the file with the correct settings for the local environment.

Then we can add the file to .gitignore, and it will not be reported as a modified file by git.

[dsolovay]

Please assign to me, I'm fixing this in my fork.