generate_schema_name should use the root-project macro definition

[drewbanin]

Right now, it uses the macro defined in the package itself (usually undefined). That's undesirable, as schemas for models inside of packages can't be configured without duplicating the macro logic inside of the package. See here

Testing

models/local_model.sql

select 1 as id

dbt_modules/package_name/models/package_model.sql

select 1 as id

macros/generate_schema_name.sql

{% macro generate_schema_name(custom_schema_name=none) -%}
  overriden_schema_name
{%- endmacro %}

^ Given the above models and macros, a dbt run should produce the following views:

• overriden_schema_name.local_model
• overriden_schema_name.package_model

Currently in dbt, the package_model will be built into the schema specified in the active profile.

[drewbanin]

We can fix this by updating the parsing code to use the context from the root project, rather than the package that the node is sourced from. That code is here: https://github.com/fishtown-analytics/dbt/blob/dev/guion-bluford/dbt/parser/base.py#L126