Config update

Copy fixes from owncloud/documentation#594 and apply them onto config.sample.php

@carlaschroder Have a look at a96f7c1 I added some fixes. Are you fine with them?

cc @PVince81 @wakeup @DeepDiver1975 @LukasReschke 
How about "This is a crucial security check on Apache servers that should always be set to``true``. This verifies that the ``.htaccess`` file is writable and correct. If it is not, then any options controlled by ``.htaccess``, such as large file uploads, will not work. It also runs checks on the ``data/`` directory. Disable this only for testing, and then remember to re-enable it.