Important Disclaimer

Added important disclaimer to the readme.md file
Enhanced readme.md

readme.md has been updated with a more descriptive version.
Added missing information to readme.md

Missing informationen about export/import of the configuration file was
added.
Hotfix

Fixed a small bug which caused the Powershell Script to crash.
Improved selection of Source folders and bugfix

Source folders can now be added through a dialog.
'no entry' won't show up at the end of the source list anymore.
Update todo.md
Removed unecessary file

The todo.md file as unecessary and was removed.
Merge branch 'development' of https://github.com/Xenplex/XenBackup into development

Conflicts:
	todo.md
Merge remote-tracking branch 'origin/development'