Remove unecessary logging statement

Signed-off-by: Ruth Byers <rbyers@pivotallabs.com>
Refactor ErrorHasher specs

Signed-off-by: Ruth Byers <rbyers@pivotallabs.com>
Refactor ErrorHasher

Signed-off-by: Ruth Byers <rbyers@pivotallabs.com>
Use whitelist instead of blacklist for exposing error information through the API

Signed-off-by: Ruth Byers <rbyers@pivotallabs.com>