title: how does omitNull work in sequelize
body: <p>I have a raw query something like this:</p>
  
  <pre><code>select c1,c2 
  from table1 t1
  where 
     t1.name :var1 AND t1.number = :var2
  </code></pre>
  
  <p>var1 and var2 are bind variables.</p>
  
  <p>Is it possible for a bind variable to be NULL. Like, if we have,</p>
  
  <pre><code>var1 = 'abc', var2 = NULL;
  </code></pre>
  
  <p>I need the resulting query to be like:</p>
  
  <pre><code>select c1,c2 
  from table1 t1
  where 
     t1.name = 'abc'
  </code></pre>
  
  <p>and not</p>
  
  <pre><code>select c1,c2 
  from table1 t1
  where 
     t1.name = 'abc' AND t1.number = NULL
  </code></pre>
  
  <p>I am passing <code>{omitNull: true}</code> in the Sequelize config (which from the doc, seems to be saying what I'm expecting in my case above), but it's not working.</p>
  
  <p>How to get this kind of behavior?</p>