Improve liquibase db script and integration test environment vars

Two unrelated changes:

1. In the liquibase-dump script: Improve how the mysql driver is obtained.
Search for the mysql-connector-java jar in the running user's .m2 directory. If it's found, use it. If not, attempt to install it via maven and use it.

2. In the integration tests: default to http://localhost:8080/v1/schemas for the cattle url so that an environment variable doesn't need set for the tests to run locally.