pcp update: better pcp2graphite error tolerance

["Frank Ch. Eigler" <fche@xxxxxxxxxx>]

Hi -

Please see pcpfans.git fche/pcp2graphite:

commit e4d49e6321d873123ba266eaf57d6f6524463f30
Author: Frank Ch. Eigler <fche@xxxxxxxxxx>
Date:   Thu Feb 19 18:12:57 2015 -0500

    pcp2graphite: tolerate errors better before/during run
    
    It was reported that for rapidly-changing indom metrics such as proc.,
    pcp2graphite would miss a report entirely if an individual metric
    encountered a PM_ERR_INST during metadata lookup.  Moving around
    python try/except blocks lets as much information pass to
    graphite/carbon as possible.
    
    qa/667 is updated to test this and a few more error scenarios using
    the sample pmda naughty metrics.