Improve multiple schema testing

Trying to use pg_tapgen on a multischema database I ran into several issues. 

* Use full schema qualified names for objects and the associated pgtap functions.
* Generate tests for Materialized Views and Foreign Tables. MV support is in head of pgtap, FT support is in a pending pull request.
* Use plan() and include explicit count of tests in generated tests. This required rewriting the output routine but I work to minimize any changes to the output.
* Removed the explicit setting of the search_path which is not a valid assumption for all databases. This removed a line of output.
* Removed 'create extension' call. This causes more problems then it solves. You can't always install an extension on a postgres server where you can always just load a .sql file. Assume pgtap has been installed before test run. 
* Added support for connecting to databases with passwords using $PGPASSWORD. For example a Heroku postgres database always has a password.
* Function list did not have an explicit ordering which resulted in output changes when no functions changed.
* Bug Fix:  Escape single quotes in column default values.