Change-Id: I9b89d433b545269d111b3c290b6411aabf58dd24

must be surrounded by quotes.

Otherwise you get a cryptic error message from Route 53.

Allow the example to be copy-pasted with minimal confusion about the error.

Change standard AWS access and secret key parameter names to aws_access_key and aws_secret_key. Fixes an authentication problem with the rds module and standardizes the naming convention on something more encompassing than ec2_*_key.

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.

The route53 api doesn't allow multiple overlapping requests, so if
it is still processing a previous request when the next comes in will
return an error.

Fixes #4085

No idea if I'm rebasing properly or not.  This is my first attempt.