new example - modify-subnet-attribute
remove output from commands that now return null
Fix example for describe-adjustment-types.
Add support for use of input  JSON skeletons

Added ``--generate-cli-skeleton`` to generate the JSON skeleton to fill out
and ``--cli-input-json`` to use that skeleton as input to a CLI command.
Add unit test for input JSON skeleton feature
Added integration test for json skeleton feature
Clean up the input json skeleton code
Update JSON code based on feedback
Add generate skeleton integ test
Accepts input shape of None
Fix arguments with no required setters
Unit and integration test pass for json skeleton
Refactor the clidriver event system
Updated the travis yml for unittest2
add frankfurt region
Updated CHANGELOG
Merge pull request #963 from kyleknap/json-skeleton

Json skeleton
Only display --page-size when operation is paginated

This moves the --page-size CLI option to the pagination customization.
Before adding the argument, we first verify that not only can the
operation be paginated, but also that the pagination configuration
supports a limit key.  This also means that the --page-size argument
is now documented on the man/html page for each operation that supports
pagination, making it more clear when this argument can be used.

The only other update was that I had to add a page size to the
S3 plugin as well.
Add --page-size argument to the aws s3 rm command

The rm command does make a ListObjects call in the recursive case,
so it makes sense to be consistent and support the --page-size argument
for aws s3 rm.
Merge branch 'page-size-in-pagination' into develop

* page-size-in-pagination:
  Add --page-size argument to the aws s3 rm command
  Only display --page-size when operation is paginated