title: not equals isnt working in cakephp3
body: <p>I couldnt get the not equals condition to work. What happens is that it is ignoring all data as the <code>cancelled_by</code> field has been <code>null</code>. If the <code>cancelled_by</code> field is <code>null</code> then that does not equate to not equals <code>Tutor</code>.</p>
  
  <p>This little error has cost me 5 days of wrong data. Is there a mistake I am making? Once I removed the not equals condition, all the data was retrieved as expected.</p>
  
  <p>The 2 lines below is what I used and neither worked.</p>
  
  <pre><code>'Lessons.cancelled_by not like' =&gt; '%Tutor%'   
  
  'Lessons.cancelled_by !=' =&gt; 'Tutor' 
  </code></pre>
  
  
  
  <pre><code>$searchDate = date('Y-m-d');
  
  $query3 = $this-&gt;find()
      -&gt;contain([
          'Tutors', 'Subjects', 'Students', 'Students.Guardians', 'XeroInvoices'
      ])
      -&gt;select([
          'Lessons.id', 'Lessons.lesson_date', 'Lessons.start_time', 'Lessons.end_time',
          'Tutors.id', 'Tutors.first_name', 'Guardians.id', 'Tutors.last_name',
          'Lessons.timesheet_status', 'Students.id', 'Students.first_name',
          'Students.last_name', 'Students.has_credit', 'XeroInvoices.invoice_number',
          'Guardians.guardian_email', 'Guardians.guardian_mobile',
          'Guardians.guardian_last_name', 'Guardians.guardian_first_name',
          'Lessons.due_date', 'Lessons.cancelled_by', 'Subjects.name', 'Lessons.revenue',
          'Lessons.discount', 'Lessons.surcharge', 'Lessons.future_makeup_lesson_id',
          'Lessons.cancelled_pastlesson_id'
      ])
      -&gt;where([
          'Lessons.due_date' =&gt; $searchDate,
          'Lessons.lesson_inactive' =&gt; false,
          'Students.has_credit like' =&gt; '%postpaid%',
          'Lessons.cancelled_by !=' =&gt; 'Tutor'
      ])
      -&gt;order([
          'Guardians.id',
          'Lessons.lesson_date' =&gt; 'ASC',
          'Lessons.start_time' =&gt; 'ASC'
      ])
      -&gt;hydrate(false);
  </code></pre>