Implement error classes, see #16
update tests to expect specific error types
update error constructors so instanceof works properly. closes #16
remove unused consumer_key arg from store implementations. closes #15
fix broken tests from previous commit
(chore) version bump 0.1.5
(chore) version bump 0.2.0
MemoryStore should be the MemoryNonceStore not a RedisNonceStore
Merge pull request #18 from jloveridge/master

MemoryStore should be the MemoryNonceStore not a RedisNonceStore