Update jiffy to 0.11.3

0.8.2 emits compile error on gcc 4.8/4.9 because of
-Wall -Werror options, so update it to latest tag.
Merge pull request #12 from yjh0502/master

Update jiffy to 0.11.3
Merge pull request #11 from efine/master

Add support for IPv6.
Use with lager via raven_lager_backend