Use hidden path filter in pathIsGood, add tests for pathIsGood
Address Oscar's comments
Merge pull request #772 from isnotinvain/alexlevenson/pathIsGood

Use hidden path filter in pathIsGood, add tests for pathIsGood
deprecate readAtSubmitter, add toIterator on Mappable
Merge pull request #774 from twitter/move-mappable

deprecate readAtSubmitter, add toIterator on Mappable