When you deploy a Project, you can select to deploy with the "Development Mode" checkbox checked.
This gives the developer several advantages, the most important of which is that changes made in the Project configuration can be immediately reloaded onto the device with the click of a button. No need to create and deploy new versions.
Devmode Refresh Button
In Development Mode, there is always a refresh button visible at the top of the screen within the action bar.
Clicking this button will download and install the latest Project configuration from the server.
The version which will show within the login screen will be "CURRENT" (i.e. not an actual version at all),