SplitYamlProvider extends and behaves similarly to YamlProvider, but
organizes the zone in multiple files by record, insteat of in a
monolithic YAML file.
YamlProvider has been slightly modified to make its extension easier.
Signed-off-by: Christian Funkhouser <cfunkhouser@heroku.com>
- adds lenient flag to Record.new, problems during validation are just
warnings if it's true
- target populate calls during the plan phase pass lenient=True
- make all of the provider.populate call logging consistent including both
target and lenient
- add source=self to Record.new in a few places that were missing it
