core.sh (parse_json): add basic support for array and object

This is poor sed parsing. So only depth 1 is handled.
An array/object containing basic types (string, numbers, boolean) is ok.

For example:
"test":{"key1":"value1",...}
"list":["key2":1234,...]

But no embedded complex types:

"test":{"key3":"value3","key3":{...}, ...}

will not be handled.

Maybe we should reconsider write something more elaborated for future.
multiup.org: add upload feature (account, using API)

Fixes issue 1020.
shareonline_biz (download): handle direct downloads (premium only)
zippyshare (download): fix, upstream changed