Story 1734: Added listing of users.

...rol-Server/src/ca/nrc/cadc/ac/server/UserPersistence.java

...rol-Server/src/ca/nrc/cadc/ac/server/ldap/LdapConfig.java

...r/src/ca/nrc/cadc/ac/server/web/users/GetUsersAction.java

...rver/src/ca/nrc/cadc/ac/server/web/users/UsersAction.java

...c/ca/nrc/cadc/ac/server/web/users/UsersActionFactory.java

...c/ca/nrc/cadc/ac/server/web/users/GetUsersActionTest.java

...a/nrc/cadc/ac/server/web/users/UserActionFactoryTest.java

...adcAccessControl/src/ca/nrc/cadc/ac/json/UsersWriter.java

...cadcAccessControl/src/ca/nrc/cadc/ac/xml/UsersWriter.java