Closes#427
- This is scaffold work for #427. Logic is done and some basic UI.
- Logic that works with free disk space is in `DiskSpaceChecker`. Use
`WrappedDiskSpaceChecker` to get live or mocked instances of `DiskSpaceChecker`.
- You can either use `mockEmptyDisk` which mocks situation when there
is enough space on disk.
- Or you can use `mockFullDisk` to mock situation when there isn't enough space on disk.
Michal Fousek
Francisco Gindre