Add debug log for pci passthrough filter

Sometimes operator need information why the host doesn't pass
the check of scheduler, this patch adds information for pci
passthrough filter if it falied to pass check.

Change-Id: Ic8fe13174fda5c75ce95fc0b64391ae081b36c6d
Partial-Bug: #1301830
Remove outdated docstring for nova.network.manager

There was related-flags section to describe config options, but was
outdated and duplicated with config options' description in code.
So We should remove it.

Change-Id: Ie0e444810393c77f04c1adbafdeb83c99d970902
Fix Resource tracker should report virt driver stats

If the virt driver provides any data for resource stats it is
lost whenever the resource tracker updates its own view of stats.
Moreover, if the resource tracker has not instances to track it
only reports the driver's view, which might be nothing.

This fix adds the driver's view of stats to the resource tracker
stats to make sure they are correctly handled.

Change-Id: Icb19148660bca542a8120ecab064551d67ac28af
Closes-bug: #1348288
Merge "Fix Resource tracker should report virt driver stats"
Merge "Remove outdated docstring for nova.network.manager"
Merge "Add debug log for pci passthrough filter"