- updated chromeDriverVersion to support running on Travis CI
- Travis CI build was failing with the message:

```
org.openqa.selenium.SessionNotCreatedException: session not created: Chrome version must be between 70 and 73
          (Driver info: chromedriver=2.45.615279 (12b89733300bd268cff3b78fc76cb8f3a7cc44e5),platform=Linux 4.4.0-101-generic x86_64) (WARNING: The server did not provide any stacktrace information)
```