title: Materialize - DropDown onclick disappear Issue
body: <p>I am using below HTML which is a <code>Dropdown</code>. On clicking the Menu Icon the DropDown pops up perfectly but doesn't disappear on clicking the Icon again.</p>
  
  <p>If I click else where on the page, the <code>Dropdown</code> disappears.</p>
  
  <pre><code>&lt;nav style="position: fixed;"&gt;
  
              &lt;!-- Dropdown Trigger --&gt;
              &lt;a href='#' data-activates='dropdown1' id="mainMenu" class="menu-dropdown"&gt;
                  &lt;i class="mdi-navigation-menu"&gt;&lt;/i&gt;
              &lt;/a&gt;
  
             &lt;!-- Dropdown Structure --&gt;
              &lt;div id='dropdown1' class='dropdown-content container'&gt;
                  &lt;div class="row icon-container"&gt;
                      &lt;div class="col s4 center-align"&gt;
                          &lt;i class="mdi-action-dashboard"&gt;&lt;/i&gt;
                      &lt;/div&gt;
                      &lt;div class="col s4 center-align"&gt;
                          &lt;i class="mdi-action-perm-phone-msg"&gt;&lt;/i&gt;
                      &lt;/div&gt;
                      &lt;div class="col s4 center-align"&gt;
                          &lt;i class="mdi-action-perm-scan-wifi"&gt;&lt;/i&gt;
                      &lt;/div&gt;    
                  &lt;/div&gt;
              &lt;/div&gt;
  &lt;/nav&gt;
  </code></pre>
  
  <p>----- Added</p>
  
  <pre><code>$('.menu-dropdown').dropdown({
                  inDuration: 300,
                  outDuration: 225,
                  constrain_width: false, // Does not change width of dropdown to that of the activator
                  hover: false, // Activate on hover
                  gutter: 0, // Spacing from edge
                  belowOrigin: true, // Displays dropdown below the button
                  closeOnClick: true
              });
  </code></pre>
  
  <p>How to disappear the Dropdown on Icon Click?</p>