Support AWS profile when accessing Glue, S3

[chronitis]

This is a (minimal) fix for #55 - direct construction of boto3.{Client,Resource} is replaced by constructing a boto3.session.Session (passing both region_name and aws_profile_name from the credentials, so they'll be used if non-null) and then using that to access resources.

[chronitis]

Rebased on 1.0.1

[grufino]

hey @chronitis only saw this now, I think we are solving the same issue but on two different places in slightly different ways: https://github.com/Tomme/dbt-athena/pull/124, we should probably stick to the same solution and use on both places (probably on others that call a new client as well)