Migrate to Nextflow

[vinjana]

Currently, the RNA-seq workflow basically is a Bash-workflow wrapped into Roddy.

• Migrate the single job into Nextflow.
• Remove/rename all references to RODDY_ from the scripts
• Migrate also the resource requirements. Start with the xl resource set
• Do not start yet refactoring jobs.
• The Nextflow workflow should run on the dkfzLsf profile using the existing environment modules.
• Document the workflow usage (example call, variables)