Add support for Framework Spec multi-tenancy

[dogeared]

Per:

https://github.com/stormpath/stormpath-framework-spec/blob/master/example-config.yaml#L10

And

https://github.com/stormpath/stormpath-framework-spec/blob/master/example-config.yaml#L113

And

https://github.com/stormpath/stormpath-framework-spec/blob/master/example-config.yaml#L181

we need to implement support for these multi-tenancy related properties.

Also, NOTE: the SpecConfigVersusWebPropertiesTest#verifyPropertiesInSpecAreInDefault must be re-enabled. It was temporarily disabled to avoid test failures related to property support differences.

See: stormpath/stormpath-framework-spec#123