Adding support for escaped identifiers in Postgresql

[dcolt]

This PR is for adding support for escaped identifiers in postgresql.

This should resolve: #1820

Example db table:

CREATE TABLE public."pageContent" (
    id bigint NOT NULL,
    "group" character varying(64) NOT NULL,
    "camelCaseName" character varying(64) NOT NULL
);
ALTER TABLE ONLY public."pageContent"
    ADD CONSTRAINT page_content_pkey PRIMARY KEY (id);

[an-tao]

@dcolt Thanks for your patch.