Configure TCP keepalive setting to all nodes

In some cases, it has been observed that services keep their
connection to RabbitMQ when they should not (e.g. during a
controller server hard reboot), creating instability. This patch
aims at fixing this by setting TCP keepalive parameters for
RabbitMQ connections, and setting kernel parameters to send
keepalive packets more often.

Change-Id: I7688a86e4ff617f20d6767f156c5d880e0d4d619
Fixes: bz#1167414
Remove RHEL6 specific code in prescript.pp

Because there are no more EPEL6 repositories on
https://repos.fedorapeople.org/repos/openstack/openstack-juno/
this code can be removed.

Change-Id: I2b212ac1121f27dbc943c86610d14b6bbb52d7b3
Packstack Plugins Clean-up

- Deleted unused import
- Pep8 compliance
- Deleted unused variables

Change-Id: I45f135b2467427cd7ee3b5ba32745af2a631458a
Signed-off-by: Gael Chamoulaud <gchamoul@redhat.com>
Use is_virtual instead of is_virtual_packstack

At least on Virtualbox is_virtual_packstack is not working.

$ grep hypervisor /proc/cpuinfo > /dev/null && echo true || echo false
false

Change-Id: I8a1fec615de3eb774950f75e38dfbf334bd81ba2
Merge "Packstack Plugins Clean-up"
Merge "Configure TCP keepalive setting to all nodes"
Merge "Use is_virtual instead of is_virtual_packstack"