Replace D-Bus with HTTP-based clients

[mvidner]

This is so WIP your eyes might hurt

Problem

When moving to the new HTTP-based architecture, we took some shortcuts. One of them was not using HTTP clients in the command-line interface. We need to adapt the following clients:

• ProductClient

• UsersClient

• StorageClient

• SoftwareClient

• LocalizationClient

• https://trello.com/c/hvPtBtMD

Solution

Short description of the fix.

Testing

• Added a new unit test
• Tested manually

Screenshots

If the fix affects the UI attach some screenshots here.