Fix cmemcahe_hash 0 values being translated to 1

[hyperair]

Some keys which should be hashed to 0 end up being hashed to 1 in cmemcache_hash. This results in a discrepancy between the server hash chosen by python-memcached and pylibmc (and other libmemcached derivatives).

Remove the or 1 that causes this.

An example of a key that is hashed to 0 by libmemcached using crc32+modula is ob.