Demo guides for Yahoo finance related demo applications

commit df48c4827e05243c137187bb0d9f157327c26b86
Author: Milind Barve <milind@datatorrent.com>
Date:   Tue Apr 1 15:04:51 2014 +0530

    Demo guide for Yahoo finance with Derby SQL demo application. #MLHR-982

commit 7b1ced0d7a18ff68c163b0b6c6628702649e1e63
Author: Milind Barve <milind@datatorrent.com>
Date:   Tue Apr 1 15:04:16 2014 +0530

    Demo guide for Yahoo finance with Alerts demo application. #MLHR-980

commit c43465d8f8235b5049bf71a30e5b95702a6f2153
Author: Milind Barve <milind@datatorrent.com>
Date:   Tue Apr 1 15:00:15 2014 +0530

    Demo guide for Yahoo finance demo application. #MLHR-981