fix typo

docker: from API 1.10 dns and volumes_from should be passed to start()

cloud/elasticache: Ensure self.data is iterable

Fix empty group name in rax.py output

Add reference to the join filter.

Fix typos in ansible-playbook man page source

Note: the man page needs to be rebuilt.

- self.data['SecurityGroups'] can return None causing traceback, if that
  is the case fallback to an empty list

Allow you to pass in arbitrary rsync options

simple random filter

Use common code for ec2_elb and ec2_elb_lb

Use common module document fragments for AWS modules

Fixes #4883

Uses the new get_aws_connection_info
and connect_to_aws common methods to reuse code

Now complains if region is not set in one of the
three possible methods

Also moved over to common documentation code so
this is actually based on #6913

Created common module doc fragment, and applied to all
modules that use ec2_connect or connect_to_aws as
they definitely share the common doc fragments

modules.rst: be consistent with service module documentation