title: Cassandra cql comparator type counter
body: <p>i want to use the following code for updating a field...<br/></p>
  
  <pre><code>@@db.execute("UPDATE user_count SET counters = counters + #{val} WHERE cid = 1 ")
  </code></pre>
  
  <p>First time i tried that i got the following fail:<br/>
  CassandraCQL::Error::InvalidRequestException: invalid operation for non commutative columnfamily user_count<br/>
  I found out that i have to use the comparator counter, but i cant find how i can setup that with the cassandra-cql gem... does anybody know how i can get this to work?
  below there is my code that does not work ...</p>
  
  <pre><code>@@db.execute("CREATE COLUMNFAMILY user_count(cid varchar PRIMARY KEY, counters counter) with comparator = counter " )
  @@db.execute("INSERT INTO user_count (cid, counters) VALUES (?,?)", 1, 0)
  </code></pre>