slapos-in-partition SR: add libnetworkcache to path of slapos.

i.e, enable cache.

software/slapos-in-partition/common.cfg

@@ -72,3 +72,20 @@ recipe = zc.recipe.egg
 eggs =
   collective.recipe.template
 
+# Add slapos.libnetworkcache to path of slapos.core.
+[slapos-cookbook]
+eggs =
+  ${lxml-python:egg}
+  slapos.cookbook
+  cliff
+  hexagonit.recipe.download
+  inotifyx
+  netaddr
+  netifaces
+  requests
+  slapos.core
+  supervisor
+  xml_marshaller
+  pytz
+  slapos.libnetworkcache
+