Improve unit tests of escape-literal/identifier, and remove them from integration tests.

Improve the code and clarity of unit tests in escape-tests.js. And
removed the related integration tests since it has been demonstrated in
the unit tests that a connection is not needed for escaping the literals
and identifiers.
Merge pull request #607 from gurjeet/improve_escape_tests

Improve unit tests of escape-literal/identifier, and remove them from integration tests.