decodeJSON: fix bug, add test
decodeJSON: fix bug, add test

Change-Id: I4fe3a2c77ad67cf1f599b65f55198f3c232e0c66
Reviewed-on: http://gerrit.aldebaran.lan/20049
Reviewed-by: pagoya <7ffac46e4411217b32d23ad04d1d8258bc41aef0@aldebaran-robotics.com>
Tested-by: pagoya <7ffac46e4411217b32d23ad04d1d8258bc41aef0@aldebaran-robotics.com>

vbarbaresi/libqi,aldebaran/libqi,aldebaran/libqi,bsautron/libqi,aldebaran/libqi