S3 credentials

[ebressert]

Thedb.to_redshift feature is great, but it does not follow the pattern of DB for database credentials. It would be great if you could put in the S3 credentials once, save it, and load it on the fly. Example of what I'd expect from the package.

from db import S3
s3 = S3(credentials)
s3.save_credentials('s3_for_redshift')
s3 = S3(profile='s3_for_redshift')
...
db.to_redshift(df, s3_cred = s3)

[glamp]

done in 410644d