core: Removed unused Roles queries

This patch removes several queries for Roles which are not used anymore.

This patch includes:
1. Removing GetRolesByAdElementIdQuery,
   GerRolesByAdElementIdAndNullTagQuery
   and GetRolesForDelegationByUserQuery.
2. Removing the VdcQueryType constants corresponding to the
   aforementioned queries.
3. Removing the GetRolesByAdElement constant from VdcQueryType, as it
   has no corresponding query class.
4. Removing RoleDAO.getAllForAdElement(Guid) and
   RoleDAO.getForAdElement(Guid) which were only used by the
   aforementioned queries. This removal includes the interfaces,
   implementations, underlying stored procedures  and tests.

Change-Id: If424d0936dc9c7dc89400c7b492febde1d2bf075
Signed-off-by: Allon Mureinik <amureini@redhat.com>