title: Assign v-validate multiple validation rules (predefined and custom)
body: <p>I can't figure out how to assign multiple rules to vee-validate. Usualy you pipe | the rules inside v-validate attribute, but the problem is that I also try to include one custom method.</p>
  
  <pre><code>&lt;input id="number" type="tel" v-model="cardDetail.number" v-card-focus
         class="form__input"
         v-validate="'required'" &lt;!-- need to add requireNumberIfCreditCard method --&gt;
         data-vv-validate-on="blur"
         name="number" required&gt;
  &lt;label for="number" class="form__label"&gt;
      {{ $root.trans.translate('cardNumber') }}
  &lt;/label&gt;
  &lt;p class="form__error" v-show="errors.has('number')"&gt;
      {{ errors.first('number') }}
  &lt;/p&gt;
  </code></pre>
  
  <p>This is my javascript</p>
  
  <pre><code>export default {
          data() {
              return {
                  cardDetail: {
                      number: '',
                  }
              }
          },
          computed: {
              requireNumberIfCreditCard() {
                  if (this.paymentMethod === 'creditCard') {
                      return this.cardDetail.number ? "required" : "";
                  }
              }
          }
      };
  </code></pre>
  
  <p>How should my HTML look like so I will be also able to add custom mthods to vee-validate? If you need any additional informations, please let me know and I will provide. Thank you!</p>