ec2_tags.py does not us-gov-east-1

[fdamstra]

ec2_tags.py still uses the legacy 'boto' interface, which has been discontinued for some time now.

This means that it doesn't work with the us-gov-east-1 region, and likely other new regions are excluded, too.

The problematic line is:

conn = boto.ec2.connect_to_region(
            region,
            aws_access_key_id=credentials['access_key'],
            aws_secret_access_key=credentials['secret_key'],
        )

Testing with a machine that can access both govcloud regions results in:

>>> print(boto.ec2.connect_to_region('us-gov-east-1'))
None
>>> print(boto.ec2.connect_to_region('us-gov-west-1'))
EC2Connection:ec2.us-gov-west-1.amazonaws.com

While this is really a boto problem, that library has been discontinued. This software should probably be rewritten to use boto3.

[fdamstra]

Created PR #212 to address this.