Formatting.
Add an example for composite key.
Add keywords for set binary operations on table forms.
Add set binary operators for relations (union, except, intersect).
Update to get composite primary key from PostgreSQL system catalog.
Add example of set binary operations.
Move data-source module into example dir.

--HG--
rename : relational-join-HDBC-pgTest/pgTest/PgTestDataSource.hs => relational-join-HDBC-pgTest/example/PgTestDataSource.hs
Move readme into example top.

--HG--
rename : relational-join-HDBC-pgTest/example/1/README => relational-join-HDBC-pgTest/example/README
Update README for examples.
Rename schema name of example1.
Merge kazu tutorial.