Fixed a minor bug in GETSET, now the SET part is not performed if the GET fails because the key does not contain a string value

SHUTDOWN now does the right thing when append only is on, that is, fsync instead to save the snapshot.

LZF compression re-enabled by default, but with INIT_HTAB set to 0 to avoid the very costly memset initialization. Note that with this option set valgrind will output some false positive about lzf_c.c

Two important fixes to append only file: zero length values and expires. A pretty neat new test to check consistency of randomly build datasets against snapshotting and AOF.

Fixed some subtle bug in the command processing code almost impossible to spot in the real world, thanks to gcov

Changed the reply of BGSAVE and BGREWRITEAOF from +OK to a more meaningful message that makes the user aware of an operation that just started and is not yet finished.

Set the master->slave logical client as authenticated on creation, so that if the slave requires a password replication works anyway

some change to redis-sha1.rb utility to make it more robust against non-meaningful changes in the dataset

a bit more verbose -ERR wrong number o arguments error, now gives info about the command name causing the error

Fixed daemonization when using kqueue/kevent. Now the server initialization is performed *after* the daemonization

use __attribute__ format in sdscatprintf() when the compiler is GCC. Fixed format bugs resulting from the new warnings.

Fixed issued #85 (getDecodedObject: Assertion 1 != 1 failed. While sorting a set), added a smarter assert() function to dump the stacktrace, provided a macro to initalize Redis objects on the stack to avoid this kind of bugs.