This commit changes several aspects of the unit test infrastructure:

  - Created config-changes.ldif file in tests/unit-tests-testng/resource/. This file is applied when the test environment Directory Server starts.
  
  - The test environment Directory Server started with TestCaseUtils.startServer() now uses non privileged ports. LDAP uses 32389 and JMX uses 33689. 

  - Added method getLdapPort() and getJmxPort() to retrieve the ports the test environment Directory Server is using.

  - Modified current test cases to use the new ports.

  - Added method getTestResource(String filename) to retrieve files the test resources folder.

  - Deprecated the fixture structure for establishing a test environment Directory Server instance. 

  - Modified schema test cases to use TestCaseUtils.startServer() instead of the fixture framework.