jp (base): new confirmOrQuit helper method to ask confirmation to user, and quit if he cancel

frontends/src/jp/base.py

@@ -546,6 +546,14 @@ class Jp(object):
         except AttributeError:
             pass
 
+    def confirmOrQuit(self, message, cancel_message=_(u"action cancelled by user")):
+        """Request user to confirm action, and quit if he doesn't"""
+
+        res = raw_input("{} (y/N)? ".format(message))
+        if res not in ("y", "Y"):
+            self.disp(cancel_message)
+            self.quit(C.EXIT_USER_CANCELLED)
+
     def quitFromSignal(self, errcode=0):
         """Same as self.quit, but from a signal handler