Added date_time_as_unix and duration extensions for active_interaction

Closes #10

LGTM given by: @esposito

Squashed commit of the following:

commit b05cc3877ccf791ef92d1af6b0cf34df702c41a2
    changelog and version
commit 754315f28c437a07a5e75c95eed46e279ac7169d
    Added date_time_as_unix and duration extensions for active_interaction