v0.4

• Fix some bugs wrongly displaying Naive-Bayes statistics as VSEARCH stats in HTML
• Allow manually specifying primers with --forward_p and --adapter_p for
  cutadapt
• Allow skipping Naive-Bayes classification via the --skip_nb parameter. This
  allows user to easily use any database with VSEARCH and generate report. See FAQ.
• Fixed bug preventing single sample heatmap from displaying
• Save versions and parameters in parameters.txt for reproducibility
• Updated QIIME 2 environment YAML.
• Fixed issue 17 reported by Stephane. Nextflow and Mamba do not need to be installed
  at base conda environment.