Add a tab-seperated output to load-into-counting

This adds a CLI flag to load-into-counting.py allowing it to output the
FPR, total number of distinct k-mers (cm-sketch occupancy) and input
files in a machine/R/excel readable format to save us from resorting to
regex hacks to pull this info out of out.kh.info etc.

I've also make the info files contain all files used as input.

I've also also added a test of the tsv creation behaviour.

Changes:
	modified:   scripts/load-into-counting.py:
			new cli flag, write all inputs to .info file
	modified:   tests/test_scripts.py:
			add test of the new cli flag