Make aptitude role faster

Aptitude role always executed ``ensure_up_to_date`` which often takes some time, albeit often it is unnecessary. 

Now Aptitude role executed ``ensure_up_to_date`` only if it actyally installs some packages, in this case when provisioning server that has all packages installed this role works significantly faster. 

As a bonus I added a call to ``apt-get update`` before installing ``aptitude`` --- this should be done.