Bugfix for previous pullrequest "Duplicate e-mail addresses: U4-315, U4-2147, U4-304"

There was a bug in the previous pullrequest that didn't allow a member
to saved if the email wasn't changed. Furthermore duplicate emails are
now prevented if requireUniqueEmail was false, but is switched to true
(when saving a member)
Merge pull request #33 from bokmadsen/6.0.7

Bugfix for previous pullrequest "Duplicate e-mail addresses: U4-315, U4-...
Moving generation of xml from ContentExtensions to the PackagingService
Fixes U4-2182 and U4-2167
Fixes U4-2234
Fixes U4-2234 including test case from issue
Merge branch '6.0.7' into 6.1.2