Add pybasedir and bindir options
Add pybasedir and bindir options

Add a pybasedir option so that it can be used for interpolation in the
default values of other options. This helps eliminate hard-coded paths
from the sample config file.

Also add a bindir option for similar reasons, but it also helps with
packaging.

Change-Id: Iadc746dcf2a24adbdf9bac945b5b330f01faeeb5

SauloAislan/ironic,rackerlabs/ironic,NaohiroTamura/ironic,dims/ironic,openstack/ironic,NaohiroTamura/ironic-lib,hpproliant/ironic,naototty/vagrant-lxc-ironic,citrix-openstack-build/ironic,emonty/ironic,ionutbalutoiu/ironic,varunarya10/ironic,froyobin/ironic,redhat-openstack/ironic,faizan-barmawer/openstack_ironic,debayanray/ironic_backup,faizan-barmawer/elytics,supermari0/ironic,ramineni/myironic,Tehsmash/ironic,dims/ironic,JioCloud/ironic,Tan0/ironic,bacaldwell/ironic,naterh/ironic,naototty/vagrant-lxc-ironic,pshchelo/ironic,faizan-barmawer/ironic-lib,SauloAislan/ironic,NaohiroTamura/ironic,devananda/ironic,openstack/ironic,openstack/ironic-lib,pshchelo/ironic,citrix-openstack-build/ironic,rdo-management/ironic,citrix-openstack-build/ironic-lib,bacaldwell/ironic,ionutbalutoiu/ironic