NoArgs-Command batch

branch containing commands that don't take arguments. 
the new commands are: Bgrewriteaof, Bgsave, ClientGetname, ClientList, ClusterSlots, Command, CommandCount, ConfigResetstat, ConfigRewrite, Dbsize, DebugSegfault, Discard, Flushall, Flushdb, Lastsave, Quit, Randomkey, Role, Save, ScriptFlush, ScriptKill, Time and Unwatch.
Encoding tests done.
The commands were not tested against a server.