Fix installing the user selected patterns

[lslezak]

Problem

• The patterns selected by user are not installed because the package manager is reset before starting the installation and the selection is lot

Solution

• Use the PackagesProposal module which remembers and restores the user selection
• Then we do not need the local @user_patterns attribute to hold the user selected patterns because it is now stored in the PackagesProposal module

Testing

• Tested manually, the selected patterns were installed

[coveralls]

coverage: 75.072% (-0.01%) from 75.084% when pulling 59656e8 on fix_pattern_selection into 35b427c on master.

[imobachgs]

Thanks!