add split reads 2 to arriba split_cnt in cff, fix logic for FC split …

[pintoa1-mskcc]

• Edit generation of CFF for arriba and fusioncatcher to improve logic. Split reads for arriba should be adding split_reads1 and split_reads2, while fusioncatcher does not separate split and spanning reads. For fusion catcher set -1 (NULL value for metafusion) for split reads, and set spanning reads value to Spanning_pairs. This will not effect the format of make_cff or metafusion. This will not alter the way metafusion functions.
• Make sure your code lints (nf-core lint).
• Ensure the test suite passes (nextflow run . -profile test,docker --outdir <OUTDIR>).
• CHANGELOG.md is updated.