In some cases the 'size' field is not available resulting in some PHP errors such as:

```json
{"reqId":"03548fd9e3d3aca15a5796b3b35d7b9d","remoteAddr":"::1","app":"PHP","message":"Undefined index: size at \/Users\/lreschke\/Programming\/core\/lib\/private\/files\/fileinfo.php#125","level":3,"time":"2014-11-17T21:38:57+00:00"}
```

This can be experienced when creating a new empty file and deleting it right away, then when going to the trash bin this error is thrown.

Fixes https://github.com/owncloud/core/issues/12188 for AppFramework apps

Check already implemented in core/settings/ajax/changedisplayname.php

The update routine tries to test the database migration before actually performing the update.

However, this will fail hard if the schema has changed (for example an unique key has been added). App developers can convert the DB in preupdate.php, however it is not called before and therefore the update fails.

This actually breaks ownCloud updates from ownCloud 6 to ownCloud 7 when the files_antivirus app is enabled.

The permissions are already catched properly on the installation so we just have to check whether the file is readable to prevent fatal errors from happening.

Fixes https://github.com/owncloud/core/issues/12135

Either we throw an exception or we ignore it. But we should certainly not print this to the end-user...

Return the real (insecure) mime type on PROPFIND

Added missing cleanPath() call that converts "/" to "" when calling
SabreDAV. This is needed because SabreDAV will discard its base URL when
passing "/".

Convert \OCP\Files\StorageNotAvailableException to
\Sabre\DAV\Exception\ServiceUnavailable for every file/directory
operation happening inside of SabreDAV.

This is necessary to avoid having the exception bubble up to remote.php
which would return an exception page instead of an appropriate response.

Equivalent to addVendorScript und addScript from OC_Util

This will use the new Hashing API for OC_User_Database and migrate old passwords upon initial login of the user.

Public interface for hashing which also works with legacy ownCloud hashes and supports updating the legacy hash via a passed reference.

Follow-up of https://github.com/owncloud/core/pull/10219#issuecomment-61624662
Requires https://github.com/owncloud/3rdparty/pull/136

* add addVendorScript & addVendorStyle
* refactoring of addScript and addStyle
* add shortcuts vendorScript and vendorStyle

Potentially fixes https://github.com/owncloud/core/issues/11678

add phpdoc

Fixes https://github.com/owncloud/core/issues/8420

...