${INSTALL_PATH} should be expanded in instructions

[Johannes Ring]

When running ./dorsal.sh on platforms where Boost is built manually by Dorsal, the following message is shown:

  After Dorsal has completed, please make sure the following
  environment variable is set before running any Python FEniCS
  programs:

  export BOOST_DIR=${INSTALL_PATH}

Would it be possible to expand ${INSTALL_PATH} to the actual install path?

[Harish Narayanan (hnarayanan)]

This is a case for ace bash hacker Joachim Berdal Haga.