Add show_exceptions configuration option to to control default ErrorHandler behavior.

Closes #68

Signed-off-by: Dane Jensen <dane@rightscale.com>
Update attributor dependency to 2.3.0.

Signed-off-by: Dane Jensen <dane@rightscale.com>
Merge pull request #82 from careo/sanitize-error-handler

Add show_exceptions configuration option to to control default ErrorHandler behavior.