Update "Exercising the Services Locally" doc

The sample config used to have several drivers enabled, but this was changed
to default to the 'pxe_ipmitool' production driver. The developer documentation
for "Exercising the Services Locally", has examples using the 'fake_ipmitool'
driver. It won't work since only the pxe_ipmitool driver is available. This adds
instructions for updating the config file to enable fake_ipmitool instead of
pxe_ipmitool.

Users sometimes encounter the 'NodeLocked' exception while trying out the
sample "ironic" commands, due to the periodic sync_power_state task locking
the node. Documentation was added with instructions on how to turn off this
background sync_power_state task via a config setting.

Change-Id: Id53db08df59d13ca7a52505d6b3c0931551f4bf4
Wait for Neutron port updates when using SSHPower

Adds a sleep after updating Neutron from the PXEDeploy driver. This only
triggers if node is configured to use the SSHPower driver. In this case, it is
presumed to be powering on virtual machines which may present a race between
it booting and Neutron processing DHCP config changes.  This is a temporary
fix until we have better synchronization with external services.  The 15s sleep
is hard-coded currently to avoid adding a temporary config setting.

Closes-bug: #1334447.
Partial-Bug: #1300589.

Change-Id: Iee40d45d34af0c44bc14c202424e919713efb78d
Merge "Update "Exercising the Services Locally" doc"
Merge "Wait for Neutron port updates when using SSHPower"