puppet: upgrade labs puppetmasters to version 3

this change will install puppet 3 on the labs puppet masters.

Some config changes are needed in puppet 3 due to a long standing bug,
see http://docs.puppetlabs.com/guides/file_serving.html#ip-addresses

Change-Id: I7df5d8c4bf86cd24772cca02218d311bc6f72c0d
Signed-off-by: Giuseppe Lavagetto <glavagetto@wikimedia.org>