add dependency and apply dependency objects

adding object types "dependency" and "apply dependency" on the same model as all the others.

Usage sample : 
  icinga2::object::apply_dependency { 'dep_mydep':
    parent_host_name => 'my_host',
    assign_where     => 'match("^azerty*", host.name)',
  }
  icinga2::object::apply_dependency { 'dep_mydepA':
    parent_service_name => 'my_service',
    object_type => 'Service',
    assign_where     => 'match("^a*", service.name)',
  }