Use SVG previews for public sharing

Add flock to config

Fix PHPDoc

Remove invalid PHPDoc

This adds a file lock to the config in hope that this prevents race conditions as reported in https://github.com/owncloud/core/issues/11070

Testplan:

- [ ] Delete config.php and make it read-only => Error is thrown that it is not writeable
- [ ] Installation still works
- [ ] Changing config settings works (i.e. using the SMTP config switches in the administration menu)
- [ ] Your PC didn't blow up
- [ ] Installing the news app and the "Disable AppCode checker" app did not destroy your installation

Only skip the main config

Otherwise read only additional configs might not be processed

Test on tmpdir

Fixes https://github.com/owncloud/core/pull/11367#issuecomment-57306037 and https://github.com/owncloud/core/issues/9218

Despite the documentation this function does not read values from the cookie

Add clickable labels to encryption recovery radios

Close the session for preview generation

Add a CLI command that creates an empty LDAP config

[sharing] group shares

Remove dead code

dn needs to be fetched to be able to detect memberOf support

Without closing the session every preview image generation is locking the session which makes the webinterface unresponsive.

Try to create datadirectory to test whether the .htaccess works

This is needed to configure the user_ldap app without using the
wizard (e.g. using tools like Puppet).

Adding test helper to test private methods

Clear up confusion of log_rotate_size config value

Add clickable radio button labels to the encryption recovery settings
pages:
* settings-admin
* settings-personal

Pressing on the radio button text now toggles the state of the radio
button.

Remove the second comment which could be confused with suggesting an invalid value: `// 100 MiB`.

To keep the easily readable example value, it has been moved into the comment header for the config item.

Added spinners in share dropdown

for whitelabeled edition, show branding name (e.g. 'ownCloud') instead of appname in header bar

Fixes https://github.com/owncloud/core/pull/11299#issuecomment-56968588 and also https://github.com/owncloud/core/issues/10628 together with https://github.com/owncloud/core/pull/11299#issuecomment-56968588 when backported.

Clicking on labels while the spinner is there will not trigger the
hidden checkbox any more.

catch and log exception in OC_Helper::cleanTmp()

Added spinners for the following actions:
- adding user
- removing user
- changing password
- toggling allowing upload
- setting a password