Scope should be configurable

[cneerdaels]

I've been joining a table in BQ, to a federated one (looks like a BQ table, but its actually a Google Sheet). It throws the error: “Encountered an error while globbing file pattern”

I've found I needed to change:
scope = 'https://www.googleapis.com/auth/bigquery'
to:
scope = ['https://www.googleapis.com/auth/bigquery', 'https://www.googleapis.com/auth/drive']

though I suppose with other federated sources, the scope may need to be configurable.

[tswast]

Thanks for the report!

Closing this as a duplicate of #38