Fix for https://github.com/netz98/n98-magerun/issues/202

Somehow the ignoreUnreadableDirs-flag for the Finder-component doesn't really ignore unreadable directory.
Merge pull request #223 from marcharding/develop

Fix for https://github.com/netz98/n98-magerun/issues/202
Merge branch 'master' into develop
[TASK] Code style change
[TASK] Added Magento CE 1.8.0.0 to download sources. Rearranged all downloader entries.
[TASK] * Added Magento CE 1.8.0.0 as installer source
       * Fixed issue #222 (by Marc Harding)
[TASK] Added Magento CE 1.8.0.0 to build Matrix
[TASK] Replaced defect tar archive of mirror 1.5.1.0 with old git checkout