Configure couchdb cluster before installing the dbs

We need to hold on deploying all couch dbs if not all configured nodes in the provider repo acutally show up as members in bigcouch. that means

• have a test if all couch nodes show up as bigcouch members
• use this test on every puppetrun on a couch node
• if it fails, display a big warning, i.e.

Warning: Not all couch nodes configured in the provider config are active bigcouch cluster members !
Creation of couchdb databases have been suspended until all members show up (otherwise the DBs would not spread over all nodes).

Please make sure to deploy to all couchdb nodes before continuing deploying to this node.
...

• optionally restart bigcouch after adding new members
• only if the test succeeds, continue with installing databases.

(from redmine: created on 2013-09-04, closed on 2014-04-17, relates #3703 (closed), relates #5269 (closed))