As a user of the enterprise edition I need an easy way to update the address database #41

For my address correction project I always have to make sure to use the 
latest address database.
Currently it involves the following steps to make sure I use the latest 
address database:
- See which version is currently installed (I have to remember that 
somehow, there is version number)
- Access the SQL Power file server, see if a newer version is available
- Download newer version if needed (> 300MB, takes a while)
- Unpack downloaded files and overwrite installed version

The following features would make it a lot easier.

Check version:
- Check every 1-2 weeks or during startup for new version of address 
database
- Add a button "Check for Updates" that looks for a newer version.

Download size:
- Create file diffs that can be downloaded instead of always having a full 
download, this would be faster and less traffic for the server.