[postgres] Fix varchar arrays in WHERE clause
[postgres] Fix varchar arrays in WHERE clause

PG JDBC driver doesn't like "character varying" when constructing arrays.
Using "text" as type works for insert/update, but results in a
  ERROR: operator does not exist: character varying[] = text[]
when used in a WHERE clause. "varchar" is the right type for the
JDBC driver

Fixes errors in:
* rails52/test/cases/adapters/postgresql/array_test.rb #test_uniqueness_validation
* rails52/test/cases/adapters/postgresql/array_test.rb #test_where_by_attribute_with_array

bruceadams/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,kares/activerecord-jdbc-adapter,kares/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,kares/activerecord-jdbc-adapter