Add Illumina/Hap.py module for germline samples with truth set.

[adamrtalbot]

Description of feature

First step to delivering validation feature as discussed in #798

Add the happy module which runs when:

• A truth set is supplied via the samplesheet (additional column required)
• --tools happy is included in commmand
• The sample has had germline short variant calling performed on it (e.g. haplotypecaller, freebayes)

Out of scope: Somatic calling, CNVs, structural variants, reporting of variants for some final validation step.

Running the module should include the stratifications and write sample to the --outdir. Results should be passed to multiqc for inclusion in the report.

[maxulysse]

I think the plan would be to benchmark output from sarek with a separate pipeline for now