Missing assert removal from sdsIncrLen()

Companion for 8eeb1802ec42682a614a5ebca318a0ba44ca7c03, but dealing with hiredis.
Merge pull request #1964 from mariano-perez-rodriguez/patch-2

Missing assert removal from sdsIncrLen()
Missing va_end also added in hiredis copy of sds.c.
Use long for rehash and iterator index in dict.h.

This allows to support datasets with more than 2 billion of keys
(possible in very large memory instances, this bug was actually
reported).

Closes issue #1814.
Cast to right type in dictNext().

This closes issue #1929, the other part was fixed in the context of issue
Fix dictRehash assert casting type.

Also related to #1929.
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.
Add Travis CI
Add automated testing for creating clusters

This script creates many different cluster configurations
by varying the number of instances and replica counts
defined at cluster initialization time.  If any cluster
topology fails to converge successfully, the entire test fails.

This script currently works on my OS X system and in a Linux VM.
It's designed to work on a CI server so it just runs
in the background and the system will report if the script
fails.
Add Redis cluster test to CI

test all the things!
Add "make 32bit" test