Add slapos stack containing parameters used everywhere

stack/slapos.cfg

+# This stack list all parameters used in every Software Release or other stack.
+# Software Releases or Stacks can safely extend this stack.
+
+[buildout]
+# Generate list of automatically chosen eggs version
+extensions +=
+  buildout-versions
+
+# Use shacache
+extends +=
+  shacache-client.cfg
+  
+# Separate from site eggs
+allowed-eggs-from-site-packages =
+include-site-packages = false
+exec-sitecustomize = false
+
+# Add location for modified non-official slapos.buildout
+find-links +=
+  http://www.nexedi.org/static/packages/source/slapos.buildout/
+
+# Use only quite well working sites.
+allow-hosts +=
+  *.nexedi.org
+  *.python.org
+  *.sourceforge.net
+  alastairs-place.net
+  dist.repoze.org
+  effbot.org
+  github.com
+  peak.telecommunity.com
+  psutil.googlecode.com
+  www.dabeaz.com
+  www.owlfish.com
+  launchpad.net
+
+# XXX: Workaround of SlapOS limitation
+# Unzippig of eggs is required, as SlapOS do not yet provide nicely working
+# development / fast switching environment for whole software
+unzip = true