Need to add config-version: 2 to dbt_project.yml for dbt 0.19

[heisencoder]

When I use dbt Cloud with dbt 0.19 prelease and with a clone of this dbt-starter-project, I immediately get an error that config-version needs to be set to 2. This is easy to fix, but is a bit of a nuisance to do for every newly created dbt project.

It looks like there were some issues raised in PR #8 with regard to branches and tagging, so maybe the main branch needs to be changed to avoid breaking earlier dbt versions.

[heisencoder]

Drew mentioned that the dbt-yml-config-version-2 branch already has the change to set config-version: 2, although this branch currently lacks the other needed change of adding a '+' in front of materialized.