Remove objectify decorator from dbapi's {get, register}_conductor()

This patch removes the objectify decorator from the get_conductor and
register_conductor dbapi's methods.

For get_condutor() method there's an objects interface to it so this patch
make the code/tests use the object interface vs direct calls to dbapi.

The problem with the objectify decorator is that dbapi methods
doesn't get the context, so when forming the RPC object using the
decorator we can't store the context within the object (which is what
we want to do to have consistent object interfaces).

Partial-Bug: 1314732
Change-Id: I1a955a59435b35277f3bbff2c02c07dd1a4c1d66
Removes get_port_by_vif

VIF is not indexed by the databse, it lives inside the extra attribute
which is a data blob, so the method is not used.

Change-Id: I11ce35bae1aa81c38c8ebc87251148ae65f3a30e
Partial-bug: 1314732
Add docs for agent driver with devstack

This allows users to run Ironic with the agent driver in devstack.

Change-Id: I9703041bde6bd1c5f19b1c732cda7e7b025aa8c1
Merge "Removes get_port_by_vif"
Remove d_info param from _destroy_images

A d_info dict was being passed to _destroy_images but wasn't used. Remove it and update calls to it. 

Change-Id: I6e50e58237d1b29b5234730099344ac432671b09
Merge "Remove d_info param from _destroy_images"
Fix tear_down a node with missing info

When tearing down a node, there could be some situations where the
instance info is missing some properties (image source deleted before
tearing down the node), so skipping node info validation. Instead,
perform a power validation to assure that the node can be power
managed.

Closes-Bug: #1335909
Closes-Bug: #1345334
Change-Id: Idb1ca720bbd19de1fccfe049e592136dbca2aacf
Merge "Remove objectify decorator from dbapi's {get, register}_conductor()"
Merge "Add docs for agent driver with devstack"
Merge "Fix tear_down a node with missing info"
Take iSCSI deploy out of pxe driver

This commit aims at separating the iSCSI deploy portions
from pxe driver so that it can reused in the newly proposed
iLO virtualmedia driver.

Implements: blueprint ironic-ilo-virtualmedia-driver
Change-Id: Id0a4b0fab797c884448a27b1cd5e3a1da05786a7