Looks like we need this after all! Oops.
Fixed image upload

Image upload widget in backend didn't work when hosting on the PHP
development server. Could be a bug in PHP itself (or rather, a
difference between the dev server and apache regarding how they fall
back to index.php for empty paths), but anyway, this should work.
Fixed #1070
Fixed a silly bug, related to #1070.

The "smart" unserializer used to be uncritically applied to all field
values; this caused text field contents that happened to be valid
serialized arrays to be displayed as just "Array" rather than the actual
text. With JSON decoding added to the smart unserializer, the same
happened with valid JSON arrays and objects, so entering something like
`[]` or `{}` or `["foo", "bar"]` in a textarea would trigger JSON
decoding.

The fix is to check the field type first, and only attempt decoding on
field types that expect it (image, file, video, etc., but not text,
markdown, html and such).
Updated CKeditor to version 4.3.4, with 'floatingspace' included.
Twig_Markup objects in video['html'] did not survive serialization

Related to #1070.

I just hope there are no other fields that try to store Twig_Markup
fields in the database...