Posibility to remove downtimes by ID

[savv3]

Scheduling downtime through Thruk API works like a charm but removing said downtime is unnecessarily hard. Currently option is to delete downtime by hostname or service name. (As far as I could find. Maybe I missed something)

[GET] /r/downtimes/ gives very nice list of all scheduled downtimes.
And [GET] /r/downtimes/[id] gives exact info for that particular downtime

Suggestion would be to add DELETE to /r/downtimes/[id] so we could easily loop over all IDs and delete them.

Full downtime list could be sorted with json filter tools and would give an exact list of IDs to delete if you don't want to delete everything.