skip activity

[marcopeg]

during a session an activity should be skipped.

it simply ends the activity duration and trigger the next step to happen.

[marcopeg]

after first spike I believe the skip should close down the step in the session model.
then the store works in order to push a data event into the log.

so the log model will contain every bits of informations about what happened during the session, it will be up to that model to use those informations to create the session data log and score.