remove horizon exercises

The horizon team keeps changing how the UI is exposed. This exercise
keeps lagging and doesn't really test anything useful any more. Just
delete it.

Change-Id: Id62904868f1d4b39e33d2ad63340b5ee2177fb56
diff --git a/exercises/horizon.sh b/exercises/horizon.sh
deleted file mode 100755
index 4020580..0000000
--- a/exercises/horizon.sh
+++ /dev/null
@@ -1,45 +0,0 @@
-#!/usr/bin/env bash
-
-# **horizon.sh**
-
-# Sanity check that horizon started if enabled
-
-echo "*********************************************************************"
-echo "Begin DevStack Exercise: $0"
-echo "*********************************************************************"
-
-# This script exits on an error so that errors don't compound and you see
-# only the first error that occurred.
-set -o errexit
-
-# Print the commands being run so that we can see the command that triggers
-# an error.  It is also useful for following allowing as the install occurs.
-set -o xtrace
-
-
-# Settings
-# ========
-
-# Keep track of the current directory
-EXERCISE_DIR=$(cd $(dirname "$0") && pwd)
-TOP_DIR=$(cd $EXERCISE_DIR/..; pwd)
-
-# Import common functions
-source $TOP_DIR/functions
-
-# Import configuration
-source $TOP_DIR/openrc
-
-# Import exercise configuration
-source $TOP_DIR/exerciserc
-
-is_service_enabled horizon || exit 55
-
-# can we get the front page
-$CURL_GET http://$SERVICE_HOST 2>/dev/null | grep -q '<h3.*>Log In</h3>' || die $LINENO "Horizon front page not functioning!"
-
-set +o xtrace
-echo "*********************************************************************"
-echo "SUCCESS: End DevStack Exercise: $0"
-echo "*********************************************************************"
-