There might be the case that `fopen($file, 'r')` returns false and thus ownCloud might believe that the config file is empty and thus potentially leading to an overwrite of the config file.

This changeset introduces `file_exists` again which was used in ownCloud 5 where no such problems where reported and should not be affected by such problems.

Ref https://github.com/owncloud/core/issues/12785#issuecomment-71548720

Add a method to set/unset multiple config values with one write

by default send mail for new server-to-server share

Don't check for `always_populate_raw_post_data` on HHVM

Do not retrieve shares through group if user has no group

HHVM seems to have problems with this at the moment (even setting those values in the php.ini of HHVM doesn't have helped much) and thus the unit test execution failed.

So it's better if we disable this check for now for HHVM.

Ignore favorites that are not available when creating the favorites list

Update SabreDAV to 1.8.12

This reduces the number of file writes we do for config.php and therefor
hopefully helps lowering the chances for empty config.php files

Also correctly return the exception for all cases when adding/removing favos

Add check for `HTTP_RAW_POST_DATA` setting for >= 5.6

Return false if the login is canceled in a hook

add config-option for an image's maximum filesize when generating previews

remove insane debug-log from OC_Image

Fix undefined offset 1 for wrong user mail address

* fixes Undefined offset: 1 at lib/private/mail.php#143

Get rid of log warning when using servercontainer

PHP 5.6 otherwise throws notices for perfectly valid code which results in broken endpoints.

Fixes https://github.com/owncloud/core/issues/13592

Fix reshare permission change to not impair other deletion code

A recent change that prevents reshare permission changes to delete group
share children had the side-effect of also preventing group share
children deletion when it needed to be done.

This fix adds an extra flag to isolate the "reshare permission change"
deletion case and keep the other ones as they were before, not only to
fix the regression but also fix other potential regressions in code that
uses this method.

Also updated the comment because now Helper::delete() is no longer
limited to reshares but also applies to group share children.

Bypass the view when storing encryption keys

[ignore] delete all server-to-server shares if a user gets deleted