message: develop is the default branch
diff: #!/bin/bash
  -# axom_code_checkout.sh branch_name
  +# axom_code_checkout.sh branch_name, if branch_name is NULL, develop is the default branch
  echo axom_code_checkout.sh 1.0
  set -ev
  rm -rf axom
  -git clone ssh://git@cz-bitbucket.llnl.gov:7999/atk/axom.git --branch $1 --recursive
  +BRANCH=develop
  +
  +if [ $1 != "" ]; then
  + BRANCH=$1
  +fi
  +
  +echo $BRANCH
  +git clone ssh://git@cz-bitbucket.llnl.gov:7999/atk/axom.git --branch $BRANCH --recursive
  cd axom
  git branch
  