Fix upgrade process when apps enabled for specific groups

add utf8 folder test

added missing User-Agents

Use proper RNG

* owncloud/UseProperRandomFunction:
  Use proper RNG generator

Scroll to uploaded file in file list

Hiding add to your own cloud if server2server sharing is not enabled

Some providers block connections with missing user-agents. Also
user-agents are useful for analyzing requests. I've added a USER_AGENT
constant that is used in cURL and in file_get_contents.

OC_Util::generateRandomBytes() only returns lowercase alphanumeric values.
We should use the new RNG which has a broader characterset.

Only return lowercase letters and digits for backwards compatbility

defaults: add customizable defaultiTunesAppId

Add some security utilities

Adding TIFF support to the files app

adding new webdav property containing the folder size

Ensure db connection before changing cache state

adding OC-ETag header

Also style submit buttons for navigation inputs

Don't automatically setup the filesystem the moment we load OC\Files\Filesystem

Fix issue where the currently logged user was causing side-effects when
upgrading.
Now setting incognito mode (no user) on update to make sure the whole
apps list is taken into account with getEnabledApps() or isEnabled().