message: Bugfix: AxomVersion.cmake was using a feature introduced after cmake_minimum_version.
  string(APPEND ...) was introduced after cmake 3.3 and Axom's cmake_minimum_version is 3.1.
diff: set(AXOM_VERSION_MAJOR 0)
  set(AXOM_VERSION_MINOR 2)
  set(AXOM_VERSION_PATCH 6)
  -set(AXOM_VERSION_FULL "v${AXOM_VERSION_MAJOR}.")
  -string(APPEND AXOM_VERSION_FULL "${AXOM_VERSION_MINOR}.")
  -string(APPEND AXOM_VERSION_FULL "${AXOM_VERSION_PATCH}" )
  +string(CONCAT AXOM_VERSION_FULL
  + "v${AXOM_VERSION_MAJOR}"
  + ".${AXOM_VERSION_MINOR}"
  + ".${AXOM_VERSION_PATCH}" )
  ##------------------------------------------------------------------------------
  ## extract_version_components( <tag>, <prefix> )
  