counter
The change allow publishing arbitrary headers via the
"storage.objects.*.bytes" counter of the swift middleware.
The list of the headers to publish can be configured in the swift
middleware filter like this:
[filter:ceilometer]
use = egg:ceilometer#swift
metadata_headers = X_VAR1, x-var2
Change-Id: I26a4a573707a778c5b86d298840e7ae25a95deea