Ignore test.native

Change-Id: I67298d72d6e9bb617ee5ad54f1d4e012cec37888
Return success, failure or exhaustion result

Previously, no result was returned by quickCheck, verboseCheck and
others: it's printed to stdout. This is rather hard to use in an
automated testing setup. This commit alters the *Check functions to
return a type denoting success, failure or exhaustion instead.

Change-Id: I92f27ca7528cd9cf18260858bb518006e39f402e
travis: add configuration files for travis-ci
travis: try and fix test build