Avoid code duplications

[maoo]

• visiblesitegroups.post and visiblesiteworkflows.post.desc.xml webscripts could be merged into one
• people.get.js and potentialmembers.get.js define the same function arrContains

[maoo]

All customisations have been marked with the RRD comment, therefore using grep -R RRD * across code should pinpoint the changes on files