Update from 2.2.7 to 2.2.8.
* A new form of dict.c (hash table implementation) iterator that performs less
copy-on-write of pages, introduced in Redis 2.2.7, caused ZINTERSTORE,
ZUNIONSTORE, SINTER, SINTERSTORE commands to behave in the wrong way.
This bug is now fixed.
* Print version info before running the test with 'make test'. This is mainly
useful for the Continuous Integration system we run.
* Fix for DEBUG DIGEST, key may expire on lookup, producing the wrong result.
* Replication with expire test modified to produce no or less false failures.
* Fixed Z*STORE when dealing with intsets, regression test added.