Setting the context path for local deployments has changed in Spring Boot 2

The current Spring seed is Spring Boot 2.0 which requires a different parameter to set the context path:

Pre 2.0: ```server.contextPath```
2.x: ```server.servlet.context-path```

See: https://github.com/atomist/sample-sdm/blob/master/src/deploy/localSpringBootDeployers.ts

This has impact on the link shown and the actual deployment of the application