Remove prerun QC as requirement to QuaC.

Currently QuaC requires that few QC tools (fastqc for raw and trimmed fastqs, fastq-helper, MarkDuplicates) be available as input. We currently run those tools as part of the small varint caller pipeline. It is desired to remove this restriction and instead make it optional for following reasons:

• When we switch to some other small variant caller pipeline than the one we developed, they are likely not to be capable of running these QC tools as part of their pipeline.

• When we publish QuaC, making them optional, instead of requirements, would allow others (both peer reviewers as well as pure strangers) to start using QuaC.