fixes #7119
fixes #7120
fixes #7121
fixes #7122

- searchByMime now correctly returns files recursively search through
  all the dirs
- added unit test for searchByMime

Fixes #7061

- fixed file name validation unit test
- added "\n" as forbidden character in isFileNameValid()

- Also fixes a few JSHint warnings in files app
- Added "global" comment on top of files app to suppress warning and
  also inform devs about what globals are use

- rename action is now checked inside of ".nametext" element
- added test to ensure that display() correctly resets all actions
  including the rename one

- for supported previews are shown with a size of 500px; icons with a size of 128px

Whent trying to upload/rename/create files in a folder that was removed
or rename, the correct error message is now shown.

In the case of upload of multiple files, the upload is cancelled.

This situation can happen if the target folder was renamed or removed
from another browser window or client.

The determineIcon() method was expecting attributes to be set which
caused warnings about undefined indices in the error log.

This fix pre-initializes the array with 'directory' and
'isPreviewAvailable' to make them disappear.

Whenever an exception occurs in the sabre connector code or code called
by it, it will be logged.

This plugin approach is needed because Sabre already catches exceptions
to return them to the client in the XML response, so they don't appear
logged in the web server log.

This will make it much easier to debug syncing issues.

- Refactored download URL building to make it overridable
- Added download URL override in public page
- Added JS unit tests for download URL
- Added OC.redirect() method to facilitate unit testing

Also added dummy table

Added "type=text" makes it look like nice like all other fields