[DRE-maint] nanoc is marked for autoremoval from testing

[Debian testing autoremoval watch]

nanoc 3.7.3-1 is marked for autoremoval from testing on 2015-07-07

It (build-)depends on packages with these RC bugs:
784768: libhiredis-dev: Transition to cmake 3.2
786669: ruby-celluloid: tests sometimes fail, causing ftbfs sometimes
787910: ruby-fog-storm-on-demand: fails to upgrade from 'jessie' - trying to overwrite /usr/lib/ruby/vendor_ruby/fog/storm_on_demand/shared.rb