fix checkstyle for files_external app, add whitespace for readability

apps/files_external/ajax/addMountPoint.php

apps/files_external/ajax/addRootCertificate.php

apps/files_external/ajax/dropbox.php

apps/files_external/ajax/google.php

apps/files_external/js/settings.js

apps/files_external/lib/amazons3.php

apps/files_external/lib/config.php

apps/files_external/lib/dropbox.php

apps/files_external/lib/ftp.php

apps/files_external/lib/google.php

apps/files_external/lib/smb.php

apps/files_external/lib/streamwrapper.php

apps/files_external/lib/swift.php

apps/files_external/lib/webdav.php

apps/files_external/templates/settings.php

apps/files_external/tests/amazons3.php

apps/files_external/tests/dropbox.php

apps/files_external/tests/ftp.php

apps/files_external/tests/google.php

apps/files_external/tests/smb.php