integration tests to self tests

[lrnzcig]

After PR #19 is merged, adding integration tests becomes low hanging fruit.

The test test_run_dot_tests runs the full DOT pipeline for the demo sample dataset. Adding checks to the results would make unnecessary to run the regression tests that we used in the legacy DOT repo.

Additionally, the following tests should not run the full DOT pipeline:

• test_dbt_log_safe.py
• test_utils.py
• test_utils_schema_improved.py
  but only the steps that are actually under test.

[dividor]

Hi @lrnzcig,

Thanks so much for PR #19, it's now merged.

Go for the low-hanging fruit!