Added tests to keep permissions of the target link on rmtree
Fixed `cygapt.utils.rmtree` for Windows

On Window the write permission is also needed.
Fixed test for testing [x86|x86_64]/setup.ini selection
Fixed the [x86|x86_64]/setup.ini selection
Merge pull request #29 from alquerci/add/test/arch

Fixed test for architecture selection
Merge pull request #28 from alquerci/fix/rmtree_on_windows

Fixed `cygapt.utils.rmtree` for Windows
Added a test for the `postinstall` command
Added the `postinstall` command
Added a test that option -y, --nopostinstall is deprecated
Added a deprecation warning when the nopostinstall option is used
Added a test for the `postremove` command
Added the `postremove` command
Added a test that option -z, --nopostremove is deprecated
Added a deprecation warning when the nopostremove option is used