added extra spec to counters
fixed problems with increment/decrement counters. Int/Longs need to be stored a string values, otherwise couchbase won't be able to increment/decrement. Note that we cannot increment a key, that is set like client.set("counter",1) because the sdk will translate it to something like \x01
Merge pull request #29 from nielsboldt/counters

added extra spec to counters