When disabled, the boto connection will be instantiated without validating
the SSL certificate from the target endpoint. This allows the modules to connect
to Eucalyptus instances running with self-signed certs without errors.
Fixes#3978
The `ec2_ami`, `ec2_elb`, `ec2_tag`, `ec2_vpc`, `route53`, and `s3` modules
all canonicalize the AWS access and secret key params as
`aws_access_key` and `aws_secret_key`. However, following the fixes for #4540,
those modules now use `get_ec2_creds` from `lib/ansible/module_utils/ec2.py`,
which requires access/secret key params to be canonicalized as
`ec2_access_key` and `ec2_secret_key`. As a result, AWS credentials passed
to those six modules as parameters are ignored (they instead always use
the AWS credentials specified via environment variables, or nothing).
So this change fixes those six modules to canonicalize the
AWS access and secret key params as `ec2_access_key` and `ec2_secret_key`,
allowing them to again accept AWS credentials passed via module params.
