Adaptation of SVR4 factory to changes required by LSARC/2008/691:
   * installation into /usr instead of /opt
   * default instance path: /var/opends instead of /var/opt/opends
   * instance.loc path: /etc/opends/instance.loc instead of /etc/opt/opends/instance.loc
   * user ldap/ldap instead of opendsd/opendsd

This also adapts the factory to be able to specify a prefix for all paths in an SVR4 package. For example, for opends package, prefix is opends.