Kill spinner process when stack.sh exits

The last spinner process active in non-verbose mode does not get killed
when stack.sh exits -- the spinner keeps spinning indefinitely.

Killing the spinner in err_exit cleans up no matter how the program
got terminated.

Because the code to kill the spinner is now called regardless of
whether spinners are in use, it has to check LAST_SPINNER_PID or the
kill command without an argument will trigger the ERR trap (or EXIT
with an error status, depending on where program execution stops).

This patch resurrects and fixes an abandoned changeset, hence:

Co-Authored-By: Adalberto Medeiros <adalbas@linux.vnet.ibm.com>

Fixes bug 1302112

Change-Id: I2d5b27971889b672361e9173bf6faf38fb1a1ec6
Fixes README.md on APACHE_ENABLED_SERVICES=keystone

The documentation stated that, to enable Keystone running on Apache,
one should set:
APACHE_ENABLED_SERVICES+=keystone,swift

However, it actually works with:
APACHE_ENABLED_SERVICES+=key,swift

Change-Id: I8cc92e9426d7fc3117b30df01babdb50576328af
Closes-bug: #1311461
Insert required iptables rules for Ironic

Devstack gate slaves have locked down local iptables firewalls.
Ironic nodes boot on an 'external' network and require TFTP
and Ironic API access back to the node via its HOST_IP.  This inserts
the required rules to the top of the INPUT chain.

Change-Id: I2e5dfa2346d45fdd549a3a3fbc255f190195cdd6
Merge "Kill spinner process when stack.sh exits"
Merge "Insert required iptables rules for Ironic"
Merge "Fixes README.md on APACHE_ENABLED_SERVICES=keystone"
Merge branch 'master' of https://github.com/openstack-dev/devstack