LB-914: Media deleting should check for (FK-based) exceptions
* fixed
LB-928: When SoundCloud API keys is wrong we don't have appropriate error message:

Fixed.
Merge pull request #288 from msat-cont/lb-914-linked-media-deleting

LB-914: linked media deleting
LB-861: On embed -> user comment, if the first filled captcha text is incorect later it will not accept it even if the correct text is provided

Build made.