unify style of config.sample.php

* use ' instead of " for config option
* place default parameters where useful into sample
* use proper comment block
* limit line size to 80 characters
re-arrange the config options and sort them in a semantical way

Conflicts:
	config/config.sample.php
Fixes in config.sample.php

* owncloud -> ownCloud
* add default value
* proper comment style
* fix line wrapping and minor typo
* remove duplication
* add Vincents proposals
* drop master config switches while backporting