shell: Use Browser 'localStorage' directly, and require it

Every browser that has WebSocket support has localStorage support.
In addition the API is quite sane, so we don't need to wrap this in
our own abstraction.

Closes #1185
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
test: Add some more test dependency lines

Closes #1186
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
shell: Correct padding for drive

Fixes #1187
Closes #1188
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>