parser couldn't handle the way Postgres collates the column-list to the
privilege: 
GRANT ALL(col1) ON TABLE table1 TO ellmkay;

This is now fixed in the parser, and a test-case is added.

were diffing in a multi-schema setup.

instead of adding 'SET search_path' statements prior to diff output (the
default behaviour), all statements will be schema-qualified.

This commit touches quite a few files in the project, and also fixes a
few privilege related bugs in passing. 

A thorough test case is also added.