Fix parsing of 'zipped' replies for various uses

As discovered in issue #523, phpredis was attempting to unserialize
both the keys *and* scores for commands like zRangeByScore.  This
had to do with the logic around deserialization in the response.

In addition, this same bug would have caused issues when running
commands like $r->config('get'), because that too, would have tried
to unserialize the values, which we don't want to do.

This commit reworks parsing and zipping up replies by allowing the
call to be configured to unseraialize any combination of keys or
values (or none or both).
Remove commented code
Merge branch 'multibulk-serialize' into develop

Conflicts:
	redis.c

References #538