Added a test for all the packages required for cyg-apt are barred
Added the package `xz` to barred package list
Merge pull request #15 from alquerci/add/xz_is_barred

Fixed the barred package list
Fix coding style
Merge pull request #16 from nylen/fix-coding-style

Fix coding style
Added some tests for `cygapt.utils.rmtree` function

Clean up following specification paths iteratively or not:
    - No exists
    - No read permission
    - Symlink to a file
    - Symlink to a directory
    - Broken symlink
Fixed `cygapt.utils.rmtree`
Merge pull request #19 from alquerci/fix/utils/rmtree

Improved test suite for rmtree
Added a backward compatibility for `skipTest` method for python 2.6