#61: Add materialized_views functions.

Add missing materialized_views functions.

    + `materialized_views_are( :schema, :materialized_views, :description )`
    + `materialized_views_are( :materialized_views, :description )`
    + `materialized_views_are( :schema, :materialized_views )`
    + `materialized_views_are( :materialized_views )`
    + `materialized_view_owner_is ( :schema, :materialized_view, :user, :description )`
    + `materialized_view_owner_is ( :schema, :materialized_view, :user )`
    + `materialized_view_owner_is ( :materialized_view, :user, :description )`
    + `materialized_view_owner_is ( :materialized_view, :user )`
    + `has_materialized_view( :schema, :materialized_view, :description )`
    + `has_materialized_view( :materialized_view, :description )`
    + `has_materialized_view( :materialized_view )`
    + `hasnt_materialized_view( :schema, :materialized_view, :description )`
    + `hasnt_materialized_view( :materialized_view, :description )`
    + `hasnt_materialized_view( :materialized_view )`

    Resolves #61.