Fix blocks arrangment and custom style losses

Moving blocks has the following problems:
- custom style of blocks in areas not affected by the moving are lost ([bugtracker](http://www.concrete5.org/developers/bugs/5-6-2-1/custom-block-design-collection-versions-design-is-lost-after-blo/))
- blocks in nested areas are kicked out of their original areas ([bugtracker](http://www.concrete5.org/developers/bugs/5-6-2-1/moving-blocks-inside-and-outside-newly-created-layouts-results-i/))

Let's fix these problems :wink: