modify isvalid option

modules/coordsi.py

         top = threshold
         bottom = -threshold
         for x in range(0, len(df)):
-            if bottom < df['acceleration'][x] < top:
-                df['isValid'][x] = 1
+            if df['frame'][x] != 0.0:
+                if bottom < df['acceleration'][x] < top:
+                    df['isValid'][x] = 1
+                else:
+                    df['isValid'][x] = 0
             else:
                 df['isValid'][x] = 0
         return df