Bug fixes

Small change in composer.json description.

Fixes the following:

• #2854654: denote all table names with curly braces

Installation error solved

As the purger plugin is declared as multiinstance delete method needs to be implemented.

fixed:
- when updating node gets deleted from eq_schedule table.
- subqueues can be used now

Note that NO upgrade path from the Drupal 7 version is provided. Main consideration to come with a stable release is the reported number of site install for the Drupal 8 version (+3K at time of writing) with relatively few issues.