[fedocal] #81: Add possibility to clean a calendar

[fedocal]

#81: Add possibility to clean a calendar
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 Reporter:  pingou       |      Owner:
     Type:  enhancement  |     Status:  new
 Priority:  major        |  Milestone:  0.4.0
Component:  fedocal      |    Version:  development
 Keywords:               |
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 This would remove all the meetings in the calendar while preserving it.

Calendar admin would be allow to do it