#156 Grid of All Active Members

1. Grid showing all active members
2. Add method in ProfilePictureFinder to get gravatar pic width/height 100px
3. Refactor of validateUrl method to handle don't break the page when you are offline (throws UnknownHostException)
4. Add of menuitem in the layout to access members page
5. Add folder plus .xhtml of members view
6. Internationalization of "profile picture" to use in "alt" attribute.