Simple test to compare implementations of LRU Caching.
PLRU is the current version of the preparedLRU code in the gocql PullRequest.
LLRU is a new version using the container/list package.
PASS
BenchmarkGetPLRU 50000 48464 ns/op
BenchmarkGetLLRU 50000 63148 ns/op
BenchmarkNotSequentialPLRU 50000 44317 ns/op
BenchmarkNotSequentialLLRU 50000 60072 ns/op
BenchmarkSetPLRU 50000 53234 ns/op
BenchmarkSetLLRU 50000 65030 ns/op