conf: Allow for non-contiguous device boot orders
conf: Allow for non-contiguous device boot orders

https://bugzilla.redhat.com/show_bug.cgi?id=889961

This patch adds the ability to configure non-contiguous boot orders on boot
devices. This allows unplugging devices that have boot order specified without
breaking migration.

The new code now uses a slightly less memory efficient approach to store the
boot order fields in a hashtable instead of a bitmap.
(cherry picked from commit 039a3283fcde23572cd93e9e09cfbfb508e5d44b)

Conflicts:
	src/conf/domain_conf.c - domain def callback stuff not backported (context)
                           - cc244e24 not backported (missing argument)

mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2