remove post setup check
Do only follow HTTP and HTTPS redirects

We do not want to follow redirects to other protocols since they might allow an adversary to bypass network restrictions. (i.e. a redirect to ftp:// might be used to access files of a FTP server which might be in a secure zone and not be reachable from the net but from the ownCloud server)

Get final redirect manually using get_headers()

Migrate to HTTPHelper class and add unit tests
ignoring writedata test in windows.
Use only lower-case letters

Fixes https://github.com/owncloud/core/issues/11239
Use non-empty defaults
Merge pull request #11211 from owncloud/previewProviderSwitch

Add a configuration switch for enabled preview mimetypes
Merge pull request #11215 from owncloud/dav-throwwhendeletefailed

WebDAV now throws 403 when deletion did not work
Merge pull request #11221 from owncloud/fix-autotest

Fix autotest.sh for whitespace in paths
Merge pull request #11227 from owncloud/fix-windows-path

fixing directory seperators
[tx-robot] updated from transifex
Merge pull request #11242 from owncloud/fix-10284

Use non-empty defaults for preview cmd line
Merge pull request #11224 from owncloud/fix_recovery_admin_user

first check if a private key exists, if not it is always a recovery szenario
Merge pull request #11226 from owncloud/kill-postsetupcheck-master

remove post setup check
Moved WebDAV and internet checks to client side JS

- Added setup checks in JavaScript
- Moved isWebDAVWorking to JS using SetupChecks
- Moved internet connection checks to an ajax call that goes through the
  server
Merge pull request #11032 from owncloud/harden-redirect

Do only follow HTTP and HTTPS redirects
Merge pull request #11241 from owncloud/use-lower-case

Use only lower-case letters
Fix share key finding algorithm in various cases

Instead of inaccurate pattern matching, use the list of users who we
know have access to the file to build the list of share keys.

This covers the following cases:

- Move/copy files into a subfolder within a share
- Unsharing from a user
- Deleting files directlry / moving share keys to trashbin
Merge pull request #11137 from owncloud/enc-pregfix

Fix share key pattern matching
Merge pull request #11234 from owncloud/fix-icon-classes

Fix icon classes, disappeared delete icon
adjust text size and opacity of drag'n'drop upload text style