Feature/cyclic hash

Adding in Cyclic Hash for K > 32 as per issues #60, #32.
Do this in a seperate testcase, one who's counting table matches the ksize of the k-mer provided
(From Jenkins: "tests.test_counting_hash.test_3_tables ... libc++abi.dylib: terminating with uncaught exception of type khmer::khmer_exception: Supplied kmer string doesn't match the underlying k-size.")