Additional functionality for Bioconductor tool integration

Upcoming functionality in `bioc_tool_init` and other features:
- `planemo bioconda_pull_request`
- `planemo bioc_tool_init --rscript` (this should parse the Rscript directly and fill in inputs and outputs directly making the tool definition file, getting requirements directly)
- Improve ``bioc_conda_recipe_init` to make both Bioconductor and R recipes

This goes with the PR https://github.com/galaxyproject/planemo/pull/492