Added modules to manage ec2 autoscaling groups

Includes management of Launch Configuration and related Autoscaling
Groups
correct version added
correct name in documentation and example
Updated modules ec2_asg and ec2_lc.

Added some missing parameters such as desired_capacity
and vpc_zone_identifier, changed some parameters to no
longer be mandatory where optionally required. Added
an 'update' option to autoscale group module.
Make ec2_asg and ec2_lc consistent with other ec2 modules

* Use ec2_argument_spec() method and then remove unnecessary
  declarations from argument_spec
* Remove AWS_REGIONS declaration
* Rename block_device_mappings to volumes to be consistent with ec2
* Remove all pep8 warnings except line length