Read digitization and sampling fractions from calibrations json files

Starting in just reconstruction.py, then propagate to others.

bin/get_calibrations

-#!/bin/bash
-
-branch=${1:-master}
-detector_benchmarks=https://eicweb.phy.anl.gov/EIC/benchmarks/detector_benchmarks/-/jobs/artifacts/${branch}/raw/
-
-mkdir -p config
-for i in results/emcal_barrel_calibration.json ; do
-  curl --fail -sL ${detector_benchmarks}/${i}?job=deploy_results --output config/$(basename ${i})
-  if [[ "$?" -ne "0" ]] ; then
-      if find ${DETECTOR_PATH} -name $(basename $i) ; then
-      echo "Warning: falling back to DETECTOR_PATH for calibration ${i}."
-      cp $(find ${DETECTOR_PATH} -name $(basename $i)) config/$(basename ${i})
-    else
-      echo "Error: could not retrieve calibrations!"
-      exit 1
-    fi
-  fi
-done