Add python-apt interface for apt-get Update
Add broken __PythonAptUpgrade() implementation
Add python-apt method for upgrade and switch it to apt-get, for now
apt's commandline parser is more stricted now

Check dbug 730362
The GUI now outputs an error message on Windows for Unix-only operations
Update manpage

Thanks: Dev Rana
Merge branch 'master' into github-master

* master:
  Update manpage
  The GUI now outputs an error message on Windows for Unix-only operations
  apt's commandline parser is more stricted now
  Add python-apt method for upgrade and switch it to apt-get, for now
  Add broken __PythonAptUpgrade() implementation
  Add python-apt interface for apt-get Update