Improved tests

[roll]

• fixes [partially] Improve test coverage #127

---

This is not covering all current goodtables data examples and test cases. We need to address full coverage later in #127.

[roll]

@pwalsh
could you please review?

[pwalsh]

@roll all good. Are we sure that it is not better to just put this stuff in testsuite and not keep all these files in here anymore?

[pwalsh]

approved, but option open to move this all to testsuite, which makes more sense to me.

[roll]

@pwalsh
I think there are a few things:

• we definitely should reduce amount of data examples here because many of them just a duplication and I suppose we lack some edge-case about csv dialects, broken encoding etc
• but still if we could provide complete test coverage (including high-level tests) on the library level - let's do it! We need great coverage on lib level to work further - accepts PRs, refactor etc. With instant feedback in dev and CI.
• so testsuite role here - to have tests which guarantee that our stack works good together (e.g. tabulator update -> tabulator tests good -> testsuite goodtables tests fail -> we've missed breaking change on tabulator level) and works after every master/PyPi change. In my opinion it doesn't mean we need just automatically move all high-level tests to testsuite - only if we can't have it on the lib level (like datapackage + jsontableschema-sql integration)