fixed bgsave_in_progress in INFO when BGSAVEing with diskstore enabled, don't DEBUG FLUSHCACHE when bgsave is in progress.

redis-cli tests commented out since there is a problem with the CI server and this tests, will be activated again once the problem is fixed

Changed redis-cli to output the raw response for a bulk reply when it is
run in interactive mode instead of checking isatty.

top level keys are no longer redis objects but sds strings. There are still a few bugs to fix when VM is enabled

tests suite initial support for valgrind, fixed the old test suite until the new one is able to target a specific host/port