Travis: Run additional 9 clients
Refactored RedisExtension
RedisExtension refactoring
Client sharding
Testing that StorageRouter uses multiple databases
ClientsPool: simpler hashing
Always register ClientsPool in extension
Benchmark: connecting a client to redis server
Benchmark: complete storage and journal benchmarking skeleton
Travis: run additional redis instances under redis user
Travis: start the redis instances before compiling extension
Fixed language level compatibility