first fix of sam's issues
fix some links. Add null=True to RateActivityInstance.rating
	modified:   LifeTracker/settings.py
	modified:   LifeTracker/settings.pyc
	modified:   README.md
	modified:   activity/models.pyc
	modified:   activity/templates/activity_detail.html
	modified:   db.sqlite3
	modified:   LifeTracker/settings.py
restrict user access to other pages. Start adding in Managers for models
	modified:   LifeTracker/settings.py