XAVIER 3.1.2

• Fix minor bug in assess_significance.R script associated with rule freec_exome_somatic. (#120, @samarth8392)
• Fix bug in multiqc docker container, which caused an error when running xavier from ccbrpipeliner/7. (#123, @kelly-sovacool)
• Fix cache subcommand to correctly read the container images config file. (#124, @kelly-sovacool)