updating kba.scorer.ccr so that it works properly with KBA 2014 truth data

These steps verify that it properly loads the truth data:

$ cat trec-kba-2014-07-11-ccr-and-ssf.after-cutoff.tsv | gzip > runs/nist-assessors.gz
$ python -m kba.scorer.ccr --any-up --require-positives=4   runs  trec-kba-2014-07-11-ccr-and-ssf.after-cutoff.tsv

Which produces these scores:

  nist-assessors
    micro_average: max(F_1(avg(P), avg(R))): 1.000
    micro_average: max(avg(SU)):  1.000
    macro_average: max(F_1(avg(P), avg(R))): 1.000
    macro_average: max(avg(SU)):  1.000
    weighted_average: max(F_1(avg(P), avg(R))): 0.007
    weighted_average: max(avg(SU)):  0.007