Add an option to reopen closed bugs/handle abuse

[KurtKrampmeier]

Someone in my area is currently abusing openstreetbugs by closing many useful unfixed bugs without adding a useful comment. Currently we would have to copy the bug report and any added comments to a new bug, but this is time consuming and might be useless as the new bug might get closed as well.

It would be nice if there was an (hidden?) option to just reopen the closed bugs. This would probably even stop the abuser from closing more bugs because it would no longer have the desired effect of causing trouble.

Hiding this from the novice user could be used as a measure against abusing this new feature itself by reopening bugs that have been fixed. But even if this feature would be public, the risk of abuse would be lower since one could only keep bugs open instead of being able to destroy useful bug reports.

Another option would be to allow only registered users to close bugs but I know this would be a lot more complicated since there is no user management at the moment.

[emka]

depends on #49