add table with fk for testing.
simple unit tests for existing functionality
data/procedure for foreign key
return a map of foreign keys
getting foreign key data with a column.
some more setup/teardown actions
fix test to reflect more tables
fix basic auth parsing
clean up spec helper
emit references for columns with foreign keys
make compound_pk owned by dbapi_anonymous
Merge branch 'fk'

Conflicts:
	src/PgStructure.hs
	test/Feature/StructureSpec.hs
	test/fixtures/schema.sql