apt module: part rewrite of the upgrade logic, consistently checking
the executable paths, adding 'safe' as an alias to yes, and adding
'full' to allow aptitude full-upgrade as an alternative to apt-get
dist-upgrade
add default=yes in upgrade argument spec
package and upgrade are not mutually exclusive, but when both were set, upgrade didn't happen
Merge pull request #2642 from sergevanginderachter/check4aptitude

apt module: part rewrite of the upgrade logic