Store the length of the static argv when first allocated.
Add regression test for issue #1939
Sentinel: Abort Hello quicker if not connected

We can save a little work by aborting when we enter the function
if we're disconnected.
Increase size of range request in getrange

32 bit builds don't have a big enough long to capture
the same range as a 64 bit build.  If we use "long long"
we get proper size limits everywhere.

Also updates size of unsigned comparison to fit new size of `end`.

Fixes #1981
Return empty string if GETRANGE of empty string

Previously, GETRANGE of a key containing nothing ("")
would allocate a large (size_t)-1 return value causing
crashes on 32bit builds when it tried to allocate the
4 GB return string.
Merge pull request #1982 from mattsta/fix-getrange-32bit

Increase size of range request in getrange
sentinel: Decouple bind address from address sent to other sentinels

There are instances such as EC2 where the bind address is private
(behind a NAT) and cannot be accessible from WAN.

https://groups.google.com/d/msg/redis-db/PVVvjO4nMd0/P3oWC036v3cJ
Sentinel: announce ip/port changes + rewrite.

The original implementation was modified in order to allow to
selectively announce a different IP or port, and to rewrite the two
options in the config file after a rewrite.
Sentinel: clarify announce-ip/port options in sentinel.conf.
Sentinel: don't set announce-ip if is empty.
Merge branch 'unstable' of github.com:/antirez/redis into unstable