Fix typos for stack.sh and lib of comments and message

Fix 10 comments and 1 message

stack.sh
  Certicate => Certificate (comment)
lib/stack
  Sentinal => Sentinel (comment)
lib/neutron-legacy
  overriden => overridden (comment)
  necesssary => necessary (comment)
  notifiy => notify (message)
  notifations => notifications (comment)
lib/rpc_backend
  orginal => original (comment)
  cofiguration => configuration (comment)
lib/stack
  confgured => configured (comment)
lib/swift
  additinal => additional (comment)
  calclution => calculation (comment)
  maximun => maximum (comment)

Change-Id: I3637388b67decb007cd49af9addecc654009559b
diff --git a/lib/rpc_backend b/lib/rpc_backend
index 03eacd8..298dcb6 100644
--- a/lib/rpc_backend
+++ b/lib/rpc_backend
@@ -58,7 +58,7 @@
         # NOTE(bnemec): Retry initial rabbitmq configuration to deal with
         # the fact that sometimes it fails to start properly.
         # Reference: https://bugzilla.redhat.com/show_bug.cgi?id=1144100
-        # NOTE(tonyb): Extend the orginal retry logic to only restart rabbitmq
+        # NOTE(tonyb): Extend the original retry logic to only restart rabbitmq
         # every second time around the loop.
         # See: https://bugs.launchpad.net/devstack/+bug/1449056 for details on
         # why this is needed.  This can bee seen on vivid and Debian unstable
@@ -106,7 +106,7 @@
     fi
 }
 
-# iniset cofiguration
+# iniset configuration
 function iniset_rpc_backend {
     local package=$1
     local file=$2