Changes with Aloha.Editor 1.2.21

Bugfix SUP-888

Some issues with cursor placement and using DELETE or BACKSPACE around blocks
in editables have been fixed.

Bugfix SUP-851

When removing all contents of a table cell, an empty paragraph
may be left behind, which is impossible to remove. In such cases,
the empty paragraph will be removed now when the focus leaves the table

Bugfix SUP-1044

When the metaview and emptyparagraph plugins were used at the same time, the
metaview plugin would override the background-color CSS rule of the
emptyparagraph plugin. This has been fixed now.