Add ldaptive-based IPersonAttributeDao.

This component will support attribute release machinery in CAS including
CredentialToPrincipalResolver components.
Move ldaptive test configuration onto test classpath.
Provide a sample resultAttributeMapping bean.
Address LdapAuthenticationHandler code review feedback.

Add allowMultiplePrincipalAttributeValues flag (default false) to handle
duplicate principal ID attribute values.
Misc code cleanup.
Merge branch 'feature-new-authn-api-ldaptive' into CRED-TO-PCPAL-RES
Minor code fixes, fixes to the javadoc.
Working on credentials to ldap resolver, combined with ldaptive person attr dao as the attr repository. Tweaked test settings to only include connection details at the extra config level.