Limit the formedOn and adoptedOn to seconds.

[ramondelafuente]

Currently, the Herd and ElePHPant models both use a DateTime type for formedOn and adoptedOn respectively.

The precision of these times can be limited to seconds, because that is the most precise value the domain is interested in. This means creating value objects that disregard the microseconds.

It also warrants the creation of a system clock that can be used to retrieve the system time.

See http://rosstuck.com/precision-through-imprecision-improving-time-objects