Feature/burgundy/pe 957 filter skipped schedule events

In versions of puppet prior to 3.3, every single agent run
    will generate a swath of skipped Schedule events, which
    are not useful and clutter up the reports data in PuppetDB.
    
This commit adds some "blacklist" functionality, whereby
    certain well-known events can be filtered in the PuppetDB
    report processor before being sent up to PuppetDB, so
    they won't be stored.
    
There is a configuration option that can be used to
    disable the blacklist, just in case these events are meaningful
    to some set of end-users.
    
The blacklist is hard-coded for now and only contains the list
    of skipped Schedule events that are well-known.