v0.17.0 package tidy up

[clrcrl]

Repo checklist:

Urgent:

• A require-dbt-version parameter in the dbt_project.yml:

require-dbt-version: [">=0.17.0", "<0.18.0"]

• The dbt_project.yml is in version 2 format (upgrading docs)
• Any sample dbt_project.yml snippets in the README.md are in v2 syntax (especially for packages that use vars
• Release is of format major.minor.patch, e.g. 1.0.0
• A license (example)
• If this package relies on dbt-utils, make sure the range allows v0.4.x

packages:
  - package: fishtown-analytics/dbt_utils
    version: ["???", "<0.5.0"]

Integration tests

If this package has integration tests:

• The dbt_project.yml of the integration tests is in v2 format
• CircleCI uses python v3.6.3
• The dbt_project.yml does not have a require-dbt-version config (it should be inherited from the package)

[clrcrl]

Closed by #53