Previously, `DriveSelector` kept a temporary selection state until the
modal was closed, which caused the selected drives to be passed to
`SelectionStateModel`.
This proves to be problematic when attempting to pass changes to
`SelectionStateModel` to `DriveSelector`. For example, consider the case
where the `DriveSelector` modal is opened with two drives, and one is
ejected. The remaining drive will be auto-selected by Etcher in the
background, but `DriveSelector` will not update itself with such change.
Fixes: https://github.com/resin-io/etcher/issues/304
Signed-off-by: Juan Cruz Viotti <jviottidc@gmail.com>