[rackspace] updated NotFound exceptions to include region when available.
[rackspace] correcting exception classes on YARD docs
[rackspace|storage] updated storage and cdn services to wrap excon exceptions in the same manner as the other Rackspace services.
[rackspace] fixing delete image tests
[rackspace] updated ServiceException to catch JSON decoding exception and display a warning message.
[rackspace|dns] updated DNS service to use Fog::DNS::Rackspace::NotFound exceptions in keeping with the rest of the services.
[rackspace|compute_v2] fixed bug in InvalidStateExceptions
[rackspace] fixing broken tests
Merge branch 'master' of github.com:fog/fog into not_found
Merge pull request #1760 from rackspace/not_found

[Rackspace] Not Found Exceptions