Encode UUIDs as 128 bit numbers not VARINTs

This fixes #43

lib/cql/protocol/encoding.rb

@@ -27,7 +27,11 @@ def write_long_string(buffer, str)
       end
 
       def write_uuid(buffer, uuid)
-        write_varint(buffer, uuid.value)
+        v = uuid.value
+        write_int(buffer, (v >> 96) & 0xffffffff)
+        write_int(buffer, (v >> 64) & 0xffffffff)
+        write_int(buffer, (v >> 32) & 0xffffffff)
+        write_int(buffer, v & 0xffffffff)
       end
 
       def write_string_list(buffer, strs)

spec/cql/protocol/encoding_spec.rb

@@ -121,6 +121,11 @@ module Protocol
           buffer.should eql_bytes("\xA4\xA7\t\x00$\xE1\x11\xDF\x89$\x00\x1F\xF3Y\x17\x11")
         end
 
+        it 'encodes a UUID as 16 bytes' do
+          Encoding.write_uuid(buffer, Uuid.new('00000000-24e1-11df-8924-001ff3591711'))
+          buffer.size.should eql(16)
+        end
+
         it 'appends to the buffer' do
           buffer << 'FOO'
           Encoding.write_uuid(buffer, uuid)