Check for statSet length
Check for statSet length

As I don't know my way round the whole codebase, I've checked for a length greater than one as this covers both the error I was getting on line 623, and a possible(?) undefined value assigned on line 626.

closes #212
XadillaX/node-memcached,3rd-Eden/node-memcached,Starefossen/memcached,jolks/node-memcached,mgetz/memcached,mgetz/memcached,fouber/node-memcached,andrewbrereton/memcached,mrlannigan/memcached,jolks/node-memcached,kbarbounakis/memcached,fouber/node-memcached,3rd-Eden/memcached,andrewbrereton/memcached,kbarbounakis/memcached,mrlannigan/memcached,acarrasco/node-memcached,mbrukman/node-memcache-client,XadillaX/node-memcached,Starefossen/memcached,3rd-Eden/node-memcached,jkrems/memcached,jkrems/memcached,mbrukman/node-memcache-client,acarrasco/node-memcached,3rd-Eden/memcached