moving CircularByteBuffer to its own class
Merge pull request #53 from broadinstitute/nh_circular_byte_buffer

moving CircularByteBuffer to its own class
First version of Picard GenotypeConcordance tool
Additional unit tests.
renaming inputs to describe truth and call samples
adding in docs for TS and CS
reversing concordance truth vs. call ordering in the output
Added optimization to only use the VCF index if scanning < 25% of the file.
Changed detailed output format.  Updated expected test output files accordingly.
Added calculation of Specificity.