Help message of configurations support i18n

Support i18n for help messages in config.py.

Change-Id: I21cc463b36a2e6a79f7cc8f64d2c2432032274cd
sqlalchemy migration not to import model

sqlalchemy migration scripts should depend on
reflections rather than import model.py
Model denotes the latest state and will fail
if used in migration scripts

Change-Id: I4fcc3d06b96fab07ed47d5cc1fc4040395a60be8
Closes-Bug: #1380479
Merge "Help message of configurations support i18n"
Merge "sqlalchemy migration not to import model"