fix #1011 -- Some content on the front page is VERY dated. This updates "Mining the Social Web" to 3rd edition, and also replaces the image with one from the third edition of the book (same dimensions). I also changed the title to be consistent with the other titles and more meaningful. I didn't run any tests.

Author: williamstein

nbviewer/frontpage.json

@@ -32,8 +32,8 @@
          "img": "/img/example-nb/python-signal.png"
        },
        {
-         "text": "O'Reilly Book",
-         "target": "/github/ptwobrussell/Mining-the-Social-Web-2nd-Edition/tree/master/ipynb",
+         "text": "Mining the Social Web",
+         "target": "/github/mikhailklassen/Mining-the-Social-Web-3rd-Edition/tree/master/notebooks",
          "img": "/img/example-nb/mining-slice.png"
        },
        {