Add dedicated time parsing method

[elbenfreund]

Right now, we use the original libs general spec to disect time information when parsing a raw_fact.

The legacy client code however allows much more elaborate time specifications as well as providing a nice parsing function.

In order to avoid reimplementing this in every client, our Controler should provide a parse_time_info method that takes care of that.

Note: This new method may also be utilized by our parse_raw_fact method at a later point.