fix#1041
* Add test-fastapi.sh script, after failing to create reusable variables in Make
* Add test-fastapi Make target
* Add fastapi dir for tests to gitignore
* Add fastapi tests to Travis
* Update test-fastapi to run the minimum (pytest)
* Move make test-fastapi to normal run, no "Without Deps"
* Install Pydantic without Cython for FastAPI tests
* Put FastAPI tests in its own Travis job
* Add PR changes description
* Remove coverage for FastAPI, it's not relevant for Pydantic
* Implement code review changes, refactor Makefile use and fastapi tests
* Add a bug intentionally, to test that FastAPI tests are using the current source
and make sure it actually breaks CI.
* Fix intentional bug. Confirmed it breaks Travis for FastAPI.
Sebastián Ramírez