LB-914: Media deleting should check for (FK-based) exceptions
* fixed
LB-814: Image post does allow comments to be added in a wrong place

Move image before contenteditable on render and
put it back into content on save.
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
Merge pull request #291 from petrjasek/lb-814-image-comments

Lb 814 image comments