Issue LIBCLOUD-471: Add ex_get_console_output method to the EC2 driver.

Signed-off-by: Tomaz Muraus <tomaz@apache.org>
Update docstring - remove obsolete comment, clarify which keys the dictionary
contains.
Fix test failure under Python 3.
Update CHANGES.
Issue LIBCLOUD-473: Add more EBS attributes to the "extra" dictionary in the
StorageVolume class.

Also refactor code to use new "_get_resource_tags" method.

Signed-off-by: Tomaz Muraus <tomaz@apache.org>
Update docstrings, fix lint issue which arose during the conflict resolution.
Update CHANGES.
Merge pull request #13 from apache/trunk

Synchronizing fork