removing unused var

Author: Bryan Kendall

lib/models/mongo/context-version.js

@@ -20,7 +20,7 @@ var keypather = require('keypather')();
 var find = require('101/find');
 var equals = require('101/equals');
 var noop = require('101/noop');
-var error = require('error');
+// var error = require('error');
 var createCount = require('callback-count');
 /**
  * d1 >= d2