Add support for more Postgres Create Table options

[wrobstory]

Hi JSqlParser maintainers!

I needed to be able to support more Postgres Create Table syntax options. Specifically, these cases:

CREATE TABLE foo (col1 integer CHECK (col1 > 100));
CREATE TABLE foo (col1 integer REFERENCES bar.col1);
CREATE TABLE foo (col1 integer CONSTRAINT no_null NOT NULL);
CREATE TABLE foo (col1 integer) WITH (fillfactor=70);
CREATE TABLE foo (col1 integer, EXCLUDE WHERE (col1 > 100));

This PR adds support + tests for these cases.

Thanks again for the great library!

[coveralls]

Coverage increased (+0.01%) to 84.136% when pulling 04c56f2 on wrobstory:pg-create-table into fefe4ac on JSQLParser:master.