Fish-compatible blt alias/function

config.fish

function blt
  if eval [[ ! -z {$AH_SITE_ENVIRONMENT} ]]
    set PROJECT_ROOT "/var/www/html/{$AH_SITE_GROUP}.{$AH_SITE_ENVIRONMENT}"
  else if [ "`git rev-parse --show-cdup 2> /dev/null`" != "" ];
    set PROJECT_ROOT "git rev-parse --show-cdup"
  else
    set PROJECT_ROOT "."
  end

  if [ -f "$PROJECT_ROOT/vendor/bin/blt" ]
    $PROJECT_ROOT/vendor/bin/blt $argv

  # Check for local BLT.
  else if [ -f "./vendor/bin/blt" ]
    ./vendor/bin/blt $argv

  else
    echo "You must run this command from within a BLT-generated project."
    return 1
  end
end