scap: ensure local copy is up-to-date; chgrp wikidev

- set ensure => latest on the Git::Clone resource so that if an application
  server is down during a scap update, Puppet will eventually update it.
- change group ownership to 'wikidev' so that scap is updateable by Bryan.

Change-Id: I1de8ff88373d9640ebafde6c638fe89b54f2e14c
Merge "scap: ensure local copy is up-to-date; chgrp wikidev" into production