Don't touch info_cache after refreshing it in Instance.refresh()

We were touching info_cache to force it to be marked dirty in the
instance object after refreshing it. However, it isn't dirty, because
it has just been refreshed and the relationship to instance hasn't
been altered. Also, the dirty state on the instance object is
unconditionally reset immediately after this anyway.

Change-Id: Ibc8e9d95210d14c946f6f820492da2331c0d7fab
Make aggregate filters use objects

Some scheduler filters that use aggregates have been converted
to use nova objects. This patch converts the remaining ones to
use objects. In both cases the calls to the database are
replaced by calls to a utility method that gets the required
data using Aggregate objects. In the future these utility
methods could be replaced with an implementation that works on
a cache - for now they do not change the behavior - its just
a refactor.

blueprint kilo-objects
Change-Id: I42d5697a67805b7e85f82cf3cf2cd6e17d923955
libvirt: enhance config memory backing to handle hugepages

Introduces a new config LibvirtConfigGuestMemoryBackingPage and
updates config LibvirtConfigGuestMemoryBacking to take advantage
of hugepages allocation for guests.

Work-Item: Enhance libvirt driver to configure guests based on
           the flavour parameter for page sizes

Partial-Implement: blueprint virt-driver-large-pages
Change-Id: I87e122a31f91448b203ba9201668f9143bf24752
Merge "Make aggregate filters use objects"
Merge "Don't touch info_cache after refreshing it in Instance.refresh()"
Merge "libvirt: enhance config memory backing to handle hugepages"