spring-clean: PlasFlow

Dependency: PlasFlow

• conda YAML file
• rm dir. in scripts/
• update path in config.yaml
• add YAML to rule(s) calling PlasFlow

Impact: Could affect the results if there are any discrepancies between the versions of any dependency. Using conda installation (plasflow=1.1.0) instead of git repo (commit v1.1-11-g82e9c75).

NOTE: release v1.1 vs. v1.1-11-g82e9c75

• README update
• changed description of arg parser in PlasFlow.py
• no other changes in the code

--> No critical changes