Bench Production environment support.

[Xieyt]

Description

Add support for bench production environment where the frappe server will run using gunicorn as configured by bench setup supervisor.

• Use gunicorn server for serving frappe.

• Add flag --environment to create and update command.
  This will be used to switch frappe environment. If environment is dev then frappe developer mode is turned on by default.

• Add flag --developer-mode to create and update command. This will be used enable/disable frappe developer mode.

[Xieyt]

Description

Add support for bench production environment where the frappe server will run using gunicorn as configured by bench setup supervisor.

* [x]  Use gunicorn server for serving frappe.

* [x]  Add flag `--environment` to `create` and `update` command.
  This will be used to switch frappe environment. If environment is `dev` then frappe developer mode is turned on by default.

* [x]  Add flag `--developer-mode` to `create` and `update` command. This will be used enable/disable frappe developer mode.

Implemented in #155.