Merge pull request mmistakes#130 from thoemmi/xing

In Germany XING is more popular than LinkedIn, so I added a link to the XING profile

Author: mmistakes

_config.yml

@@ -43,6 +43,7 @@ owner:
   github: #username
   stackoverflow: #http://stackoverflow.com/users/123456/username
   linkedin: #username
+  xing: #username
   instagram: #username
   lastfm: #username
   tumblr: #username

_includes/_author-bio.html

@@ -12,11 +12,12 @@
 
   <h3 itemprop="name">{{ author.name }}</h3>
   <p>{{ author.bio }}</p>
-  {% if author.email %}<a href="mailto:{{ author.email }}" class="author-social" target="_blank"><i class="fa fa-fw fa-envelope-square"></i>Email</a>{% endif %}
+  {% if author.email %}<a href="mailto:{{ author.email }}" class="author-social" target="_blank"><i class="fa fa-fw fa-envelope-square"></i> Email</a>{% endif %}
   {% if author.twitter %}<a href="http://twitter.com/{{ author.twitter }}" class="author-social" target="_blank"><i class="fa fa-fw fa-twitter-square"></i> Twitter</a>{% endif %}
   {% if author.facebook %}<a href="http://facebook.com/{{ author.facebook }}" class="author-social" target="_blank"><i class="fa fa-fw fa-facebook-square"></i> Facebook</a>{% endif %}
   {% if author.google.plus %}<a href="http://plus.google.com/+{{ author.google.plus }}" class="author-social" target="_blank"><i class="fa fa-fw fa-google-plus-square"></i> Google+</a>{% endif %}
   {% if author.linkedin %}<a href="http://linkedin.com/in/{{ author.linkedin }}" class="author-social" target="_blank"><i class="fa fa-fw fa-linkedin-square"></i> LinkedIn</a>{% endif %}
+  {% if author.xing %}<a href="http://www.xing.com/profile//{{ author.xing }}" class="author-social" target="_blank"><i class="fa fa-fw fa-xing-square"></i> XING</a>{% endif %}
   {% if author.instagram %}<a href="http://instagram.com/{{ author.instagram }}" class="author-social" target="_blank"><i class="fa fa-fw fa-instagram"></i> Instagram</a>{% endif %}
   {% if author.tumblr %}<a href="http://{{ author.tumblr }}.tumblr.com" class="author-social" target="_blank"><i class="fa fa-fw fa-tumblr-square"></i> Tumblr</a>{% endif %}
   {% if author.github %}<a href="http://github.com/{{ author.github }}" class="author-social" target="_blank"><i class="fa fa-fw fa-github"></i> Github</a>{% endif %}