cache directory of singularity

[444thLiao]

Dear all,

I recommend adding envWhitelist = 'SINGULARITY_LOCALCACHEDIR' in the nextflow.config to make the env SINGULARITY_LOCALCACHEDIR usable in nextflow. This env could designate the location to which singularity images extract. For some nodes, the small /tmp might make the mount failed.

Furthermore, the latest version of vibrant (v1.2.1) has reconstructed the parameters. Thus, I think we better update the version of vibrant and pass the database instead of database.tar.gz every time.