ec2_asg module enhancements

  - Added a more verbose response
  - includes its settable attributes and a list of its instances.
  - allows setting of tags, changes upon which mark the task changed
  - allow getting of information from asg module, not just setting
  - doesn't mark changed if the parameter wasn't specified
  - Availability Zones are pulled from the region
Merge branch 'ec2_asg_info' of https://github.com/dataxu/ansible into dataxu-ec2_asg_info
Fixing doc typos and adding version_added for tags param in ec2_asg
Merge branch 'dataxu-ec2_asg_info' into devel