Set viewer mode to filelist when viewing ODF file

Now calling FileList.setViewerMode() to properly toggle viewer mode.
This will hide the sidebar and actions automatically.

Note: I've removed the fade animation because:
1) It was too slow
2) It is the responsibility of the file list (toggling view mode) to trigger animations, not every app deciding on their own (for consistency). For now there is no animation from FileList.setViewerMode() but we could add one later.

@VicDeo @owncloud/designers