Added support for running kmergenie in QC stage

What the title says. Runs kmergenie to get a recommended kmer size for the data, generates a png plot (because pdf plots :-1: ) and adds a section to the report.
Sorry to be picky with this, but can't you give it a try? Such a long lines are just unreadable :-/ Not saying that you should review all the code, but _at least_ for new code like this.. eller hur? :-)