Merge branch 'release-1.6.7' into develop

* release-1.6.7:
  Bumping version to 1.6.7
  Update changelog with service updates
  Update requirements and changelog for opsworks
  Add ``opsworks register`` command.
  [EMR] Add a working streaming steps example to add-steps and create-cluster
Don't print unicode escape sequences for non-ascii chars

Also, we need to use the get_stdout_text_writer because of a
bug in py2.6 in which the `.encoding` attribute is not honored
for `sys.stdout` (http://bugs.python.org/issue4947).

Fixes #1048.
Restrict encoding test to non-windows platforms
Add issue to changelog
Merge branch 'print-unicode' into develop

* print-unicode:
  Add issue to changelog
  Restrict encoding test to non-windows platforms
  Don't print unicode escape sequences for non-ascii chars
Fix iam create-virtual-mfa-device to work with relative output paths.

This commit also cleans up some of the test module code including:

* pep8 formatting
* remove unused imports
* switchover to assert_params_for_cmd2.
Add issue to changelog
Merge branch 'quiver-fix-iam-CreateVirtualMFADevice-for-relative-outfile-path' into develop

* quiver-fix-iam-CreateVirtualMFADevice-for-relative-outfile-path:
  Add issue to changelog
  Fix iam create-virtual-mfa-device to work with relative output paths.
Bump version of six to match botocore
Merge pull request #1054 from kyleknap/bump-six

Bump version of six to match botocore
Bumping version to 1.6.8
Merge branch 'release-1.6.8'

* release-1.6.8:
  Bumping version to 1.6.8
  Bump version of six to match botocore
  Add issue to changelog
  Fix iam create-virtual-mfa-device to work with relative output paths.
  Add issue to changelog
  Restrict encoding test to non-windows platforms
  Don't print unicode escape sequences for non-ascii chars