github-card.html

<dom-module id="github-card">
  <style>
  </style>

  <template>
    <iron-ajax
      id="getCard"
      handle-as="json"
      on-response="handleResponse">
    </iron-ajax>
    <div>
      <paper-card heading="{{name}}" image="{{profile.avatar_url}}">
        <div class="card-content">
          Followers: <span>{{profile.followers}}</span>
          Following: <span>{{profile.following}}</span>
          <article>
            <p>{{profile.bio}}</p>
          </article>
        </div>
      </paper-card>
    </div>
  </template>

  <script>
    Polymer({
      is: 'github-card',
      properties: {
        user: String,
        profile: {
          type: Object,
          value: {}
        },
        name: {
          type: String,
          computed: 'computeName(profile)'
        }
      },
      handleResponse: function (response) {
        this.profile = response.detail.response;
        console.log(this.profile);
      },
      computeName: function (profile) {
        return profile.login + '\'s ' + 'Github profile';
      },
      ready: function () {
        var ajax = this.$.getCard;
        ajax.url = 'https://api.github.com/users/' + this.user;
        ajax.generateRequest();
      }
    });
  </script>
</dom-module>

index.html

<github-card user="tfarla">