title: It is not working on data-parsley-mincheck="2" with Parsley.js-2.0.0-rc4
body: <p>When I check my form, it show 'Y' in console. But I did not select any checkbox.<br/>
  In official document, it say:</p>
  
  <blockquote>
    <p>checkbox need to have either a name or an id attribute to be correctly
    binded and validated by Parsley. Otherwise, they would be ignored and
    a warning will be put in the console.</p>
  </blockquote>
  
  <p>I had set 'name' attribute in input tag and parsley also did not show:</p>
  
  <blockquote>
    <p>To be binded by Parsley, a radio, a checkbox and a multiple select
    input must have either a name, and id or a multiple option.</p>
  </blockquote>
  
  <p>But it still not work on data-parsley-mincheck="2". <br/><br/>
  In other situation, the same code is work on parsley-mincheck="2" with parsly version 1.2.3.<br/><br/>
  So, if I have any mistake with the official document (parsly 2.0.0-rc4).</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
      &lt;head&gt;
          &lt;title&gt;Test&lt;/title&gt;
          &lt;script src="jquery-1.11.0.min.js"&gt;&lt;/script&gt;
          &lt;script src="parsley.min.js"&gt;&lt;/script&gt;
          &lt;script&gt;
              function checkMyForm(myform) {
                  if($(myform).parsley().validate()) {
                      console.info('Y');
                  } else {
                      console.error('N');
                  }
              }
          &lt;/script&gt;
      &lt;/head&gt;
  
      &lt;body&gt;
          &lt;form name="myform" action="" method="post" novalidate onsubmit="return false;"&gt;
              &lt;div&gt;
                  &lt;input name="mybox" type="checkbox" value="1" 
                          data-parsley-multiple="mytest"
                          data-parsley-mincheck="2" /&gt;&amp;nbsp;Value-1&amp;nbsp;&amp;nbsp;
                  &lt;input name="mybox" type="checkbox" value="2" data-parsley-multiple="mytest"/&gt;&amp;nbsp;Value-2&amp;nbsp;&amp;nbsp;
                  &lt;input name="mybox" type="checkbox" value="3" data-parsley-multiple="mytest"/&gt;&amp;nbsp;Value-3&amp;nbsp;&amp;nbsp;
                  &lt;input name="mybox" type="checkbox" value="4" data-parsley-multiple="mytest"/&gt;&amp;nbsp;Value-4&amp;nbsp;&amp;nbsp;
                  &lt;input name="mybox" type="checkbox" value="5" data-parsley-multiple="mytest"/&gt;&amp;nbsp;Value-5&amp;nbsp;&amp;nbsp;
              &lt;/div&gt;
              &lt;!-- &lt;div style="padding: 10px 0px;"&gt;
                  &lt;input name="mytext" type="text" data-parsley-required="true"/&gt;
              &lt;/div&gt; --&gt;
              &lt;a href="javascript: checkMyForm(document.myform);"&gt;Test Checkbox&lt;/a&gt;
          &lt;/form&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>I find some similar question about it:<br/>
  <a href="https://stackoverflow.com/questions/22085202/how-can-i-get-parsley-js-to-oupt-1-error-for-a-group-of-radio-buttons-or-checkbo">How can I get Parsley.js to oupt 1 error for a group of radio buttons or checkboxes?</a></p>
  
  <p>I try to change my data-parsley-mincheck="2" to the last checkbox and add required attribute.<br/>
  When I check my form again, it also return 'Y' (But I did not select any checkbox).<br/>
  Thus, it is not the key point on the problem.</p>