Tweak singularity container deploy

• Default install.sh to the nightly install
  • Make sure container fetch for the nightly version works (might be a conflict with the regular master?)
• Add optional positional arguments to install.sh to allow the installation of alternate container version
• Add secondary installer download_dev.sh to essentially wget the dev container into a prefix (without any launcher scripts)
  • Document commands to deploy the dev container, with clear WARNING notice that this is for expert use only.
• Automatically bind main prefix and some standard locations into the container
• Hard-code container version and build date into /etc/jug_version, and print this on container start
• Add eic-info script to print container info
• Fix #64 (closed)