Update version to 1.2.0

src/jsone.app.src

@@ -1,6 +1,6 @@
 {application,jsone,
              [{description,"Erlang JSON Library"},
-              {vsn,"1.1.0"},
+              {vsn,"1.2.0"},
               {registered,[]},
               {applications,[kernel,stdlib]},
               {contributors,["Takeru Ohta"]},