Implemented normalization by organism

blast2bsrGraph.py now computes a global average bit score ratio, and one
for each pair of organisms (including self-hits), and then uses a ratio of
the global average BSR to the inter-/intra-organism average BSR to normalize
the graph edges.  I also added some more scripts for testing, and results from
a test data set of CEGMA genes in which all genes from certain organisms have
been fragmented into 2-3 pieces.

Signed-off-by: Ted Gibbons <ted.codes@gmail.com>