Docker image

[martinkilbinger]

Summary

This PR add functionality to make a docker container run with shapepipe on canfar.
Changes:

• Dockerfile updated to have sextractor and psfex installed from conda.
• Added script to initialise conda env on canfar
• Added script to call curl to run headless container on canfar.
• Added nsswitch script to make things run smoothly on canfar (recommendation from Seb Fabbro).
• Remove most library versions from environment.yml since they created fatal version inconsistencies
  (to be reviewed)
• Removed pysap and mccd from requirements due to installation errors in those packages
  (to be reviewed)

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