Update Tests for Input Validation

This patch updates the tests, to reflect the API changes in input
validation. This includes adding new data driven tests and removing some
tests that are better addressed unit tests.

Tests: bp input-validation
Tests: bug #1212389

Change-Id: I8e09541b8bfa1e23804e3d13490ff755646f2127
chore: remove unneeded statements in wsgi

1. Falcon response's status defaults to 200, no need to set it;
2. Message posting count checking is already covered by input
   validation.

Change-Id: I905dba8bb55e6a4254b2625bb9b71c51496fd2a8
Merge "Update Tests for Input Validation"