fixes delete folder on XP
- added implementation for ShowSaveDialog on Linux
fix whitespace
Merge pull request #314 from adobe/irichter/showSaveDialogLinux

- added implementation for ShowSaveDialog on Linux
Merge pull request #313 from adobe/jeff/fix-delete-folder-win-xp-rb

Fixes delete folder on XP
Implements the following brackets Shell APIs on Linux:

* brackets.fs.copyFile
* brackets.app.getUserDocumentsDirectory
Merge pull request #315 from adobe/jeff/linux-fs-api-impl

Implement missing APIs on Linux