Resize array in remove_from_array() and fix a crash

Resize array in remove_from_array() and fix a crash

When an item is added to an array, then the array is realloc()ed (to size+1),
and the item is copied (strdup()) to the array.
Thus, when an item is removed from an array, allocated memory pointed by
the item (not the item itself) should be freed, successive items should
be left-shifted and the array realloc()ed again (size-1).

Additional changes:
- Initialize an array in list_all_containers().

Signed-off-by: Tomasz Blaszczak <tomasz.blaszczak@consult.red>