Quoted keys in cases.json and removed allow_barekey from grains.t as it is not implemented in JSON::XS
Merge pull request #31 from sillymoose/master

grains.t fixes
added leap exercism, updated and sorted EXERCISES.txt
renamed leap/Leap.pm to leap/Example.pm. Tidied test titles.
Add luhn exercise
Merge pull request #33 from bistik/luhn
Added robot-name exercism, updated EXERCISES.txt
Add hamming exercise
Merge pull request #34 from bistik/hamming
Merge pull request #32 from sillymoose/master

Merged leap, robot-name. Thanks!