Improve database configuration of integration tests

Description

http://forum.liquibase.org/topic/integration-tests#49382000000282100

From forum post:
I now see that the
database connection information is in the constructor for various
database specific test cases.

I see that you have a liquibase.integrationtest.local.properties file
which allow for the host name to be set. I think that it would be
helpful to expand the use of this properties file to specify the url,
username, and password for each of the database types (with the
default values in liquibase.integrationtest.properties). It would
also be helpful to add a setting for each database type to skip those
tests from executing (like if you don't have a SQL server instance to
test with).

With just a few minor changes and a README, almost anyone can copy the
default properties, modify for their env, and run the tests in their
env without having to make any code changes.

Environment

None

Reporter

QuintonM

Affects versions

Priority

Minor
Configure