Indentation fixes
Use correct icon/name when moving existing blocks

When moving blocks already in the page, use the correct icon/name instead
of the generic "Content".

If, for any reason, the correct icon/name isn't found, we still fallback
to the "Content" block, but with a localized name.
Simplify handling of dragging avatar

Let's adopt a common "data-dragging-avatar" attribute when adding new
blocks and when moving existing blocks.
Better handling of long block type names
Merge pull request #156 from mlocati/use-blocktype-icon-name-on-move

Use correct icon/name when moving existing blocks