Make sure that all arguments that should be optional are actually optional

[fblundun]

Example: track_screen_view shouldn't require an id argument but currently does.
More keyword arguments is probably the best way to do this.

[alexanderdean]

Agree

[fblundun]

This is now in 0.2.0, rescheduling...

[alexanderdean]

Fixed in 0.2.0, closing