couch node: same packages removed on every (second ?) puppetrun

same as #3960 (closed), but for couch nodes

   - [urchin] notice: /Stage[main]/Ruby/Package[ruby-dev]/ensure: ensure changed 'purged' to 'present'
   - [urchin] notice: /Stage[main]/Site_config::Packages::Base/Package[cpp]/ensure: removed
   - [urchin] notice: /Stage[main]/Site_config::Packages::Base/Package[libc6-dev]/ensure: removed
   - [urchin] notice: /Stage[main]/Site_config::Packages::Base/Package[cpp-4.7]/ensure: removed

(from redmine: created on 2014-01-21, closed on 2014-03-26, relates #3960 (closed))