allow option for showing of "0"  on countdown

Currently if a unit of time has 0 (as in, 0 minutes or 0 seconds) but has a larger unit behind it, that unit disappears.

example:
```
30d 9h 1m
30d 9h 59s
```

a more desirable look could be:
```
30d 9h 1m 0s
30d 9h 0m 59s
```
