Fix #432: Siena installation error

Tests show that there is no error if the answer is piped from `yes`.

installer.py

@@ -258,7 +258,7 @@ class Installer:
     self.__run_command("mv play-1.2.5/play play-1.2.5/play1")
 
     # siena
-    self.__run_command("play-1.2.5/play1 install siena", send_yes=True)
+    self.__run_command("yes | play-1.2.5/play1 install siena")
 
     ##############################
     # TreeFrog Framework