More don't catch `SystemExit`

Fixes #5159 `file` module: Don't catch `SystemExit`

tests depend on the default encoding being utf8

Fix for issue #4730 - stacktrace when deferenencing a non-existent group

Make sure ssh pipes are empty before moving on

Fix issue #5214: hostname persistence on RedHat/CentOS

Prevents UnicodeEncodeError

Fix checking for existence of EC2 tags

Fixes #5081

Avoid a traceback when using accelerate

fix heading name syntax in AWS guide

This bit of code is attempting to access accelerate_inventory_host,
which may not have been set/created. This will cause a traceback.
Instead use getattr with a fallback to False.

Fixes #5064

Fix AWS credential params for ec2_ami, ec2_elb, ec2_tag, ec2_vpc, route53, and s3 modules

fixed documentation typo about region purpose

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.

fixed typo for assemble function

Update unarchive

Modified argument order provided to unzip command as the -o was being interpreted as a file.

Remove Python 2.4-incompatible 'with' statement