update tests to use output files

[bitner]

Updates and fixes for tests

• Fixes Invalid parse while combining AND and OR clauses #44
• Updates tests for Invalid parse while combining AND and OR clauses #44 (supersedes Failing test for #44 #45)
• Add pg_escape for quoting Identifiers and Literals with escapes
• Change how expected tests work so the input, cql2 text output, and cql2 json output are in a single file to make it easier to review the expected outputs
• Update the generate-expected script
• Fix is null / is not null issue found with updated tests