Add logging to PeepholePermalink's RunListener

Also, I changed the behavior in `onDeleted(Run)`:

It shouldn't matter whether a deleted build qualified for an existing permalink (`apply`) if the permalink points to it. Not sure what the rationale here is, perhaps copy&paste from `onCompleted(Run)`?

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Text samples:

    Mai 21, 2014 10:13:10 PM FINE jenkins.model.PeepholePermalink
    Updating lastStableBuild permalink updated to completed 6
    Mai 21, 2014 10:13:10 PM FINE jenkins.model.PeepholePermalink
    Updating lastSuccessfulBuild permalink updated to completed 6
    Mai 21, 2014 10:13:21 PM FINE jenkins.model.PeepholePermalink
    Updating lastStableBuild permalink from deleted 6 to 3
    Mai 21, 2014 10:13:21 PM FINE jenkins.model.PeepholePermalink
    Updating lastSuccessfulBuild permalink from deleted 6 to 3