[issue4847] Uninvites no longer cause a mail to be sent (RT#10123)

Steps to reproduce:

Two Users A and B
1. A Creates an Event and invites User B
2. A clicks Ok on the question to sent the invitation mail.
3. A Edits the Event and removes B from the attendee list.

> A Is not asked if he should sent an update to the participants.
This is wrong
A should be asked to sent an update and B should then be notified that he is no
longer invited to this Event with the option to remove it from his calendar.

This worked in old versions.
Tested Versions: 
enterprise35 0.20100924.1179069 < OK (works as expected)
enterprise35 0.20110627.63330a1 < Broken (shows current behavior)
enterprise35 20120531.96242d5 < Broken (Shows current behavior)

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assignedto: aheinecke
keyword: enterprise35, kde client, kkc
messages: 28728
nosy: aheinecke, allen, emanuel, laurent, ludwig, sergio, till, vkrause
priority: urgent
status: unread
title: Uninvites no longer cause a mail to be sent (RT#10123)

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Kolab issue tracker <[email protected]>
<https://roundup.kolab.org/issue4847>
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