Finalized incremental attributes retrieval support.
Integrated incremental attributes retrieval support in compansating transaction classes.
Integration tests for Active Directory (not enabled on CI machine).
This commit converts the build to a Gradle based build. It also setup sonar
integration at https://sonar.springsource.org/dashboard/index/11620
Currently tests in the samples fail on the CI server and are disabled. The
tests were not enabled for the maven based build either.
Issue: LDAP-251