Read/Write files on specific S3 accounts
Say I want to save a file to S3 using a specific account:

```
df.to_csv('s3://foo/bar/temp.csv')
```
where my accounts are listed in `~/.aws/credentials`:

```
[default]
aws_access_key_id = XXXX
aws_secret_access_key = XXXX

[foo]
aws_access_key_id = XXXX
aws_secret_access_key = XXXX

[bar]
aws_access_key_id = XXXX
aws_secret_access_key = XXXX
```

What's the best or recommended way to do this with Pandas `0.20.2`? 

Any way to use/specify what account to use when we have multiple of them?

Perhaps related: Does Pandas use `boto` or `boto3`?