Change for team activity page GET params

I think page is better to use since it's used for other pages.  Added
some code to handle ValueErrors when converting the number.
Simplified Action.objects.for_team()

Removed the ids param.  That doesn't really improve performance now
that we are not doing the count() query.

Removed the select_related().  I think it's better for the code that
calls for_team() to set that, since that code knows better what
related fields will be needed.
Merge pull request #1784 from pculture/more-team-activity-changes

More team activity changes