Cityhash 1.1.0

[rmg]

Updates CityHash to v1.1.0 from Google. Since v1.1.0 changes some of the hashing algorithms, I've updated all the tests as well.

Tested on OS X with clang 4.2 and GCC 4.2.1, with -msse4.2 and without.

As discussed in #7, this change is NOT backwards compatible due to changes in hashing, so a new release branch would probably be a good idea.