Script variables

Environment variables needed in scripts:

• HDA_APP_DIR: Directory of the webapp (basically, PWD)
• HDA_IP: the internal IP of the HDA
• HDA_APP_NAME: App name
• HDA_DOMAIN: internal domain of this HDA
• HDA_APP_USERNAME: admin username (if available, otherwise undefined)
• HDA_APP_PASSWORD: admin password (if available, otherwise undefined)