v0.4.0

1. Deprecated old flags --use-docker and --use-singularity.
   --docker and --singularity can work as flags too.

   $ caper run atac.wdl --docker  # this will use docker image defined in WDL
   $ caper run atac.wdl --docker docker_image_location

2. caper init
   Choose a platform and caper will auto-generate default configuration file (~/.caper/default.conf) with only required parameters for a chosen platform.

   $ caper init sherlock

3. Others

• A file DB is now compressed.
• Better error checking and troubleshooting.