Modifies the schema tests to return a pass/fail exit code
This means we can make the tests play nicely with travis

The travis.yml script needs alteration to incorporate these changes
Modifies the .travis.yml file to also run the schema tests as part
of the tests on making a commit.
Merge pull request #134 from IATI/exit-code-tests

Modifies the schema tests to return a pass/fail exit code