2.13.0 - Detect decimated files

Combined decontamination task will now correctly detect "decimated" samples which have very few reads. This should save time and money in myco as it prevents moving onto the variant caller, and also prevents rare bugs where the variant caller freaks out due to coverage issues (most typically this manifests as having enough reads for samtools but not cortex, but it seems there's a few other possible failures too).

What's Changed

• Fix print bugs, fail tiny files in check and decontam task by @aofarrel in #36

Full Changelog: 2.12.2...2.13.0