mark block-image placeholder as ephemera while inserting - remove empty semantic blocks on cleanup
remove console-log from semantic-block js
Merge branch 'master' into ticket-423

Conflicts:
	src/plugins/oer/semanticblock/lib/semanticblock-plugin.js
Merge pull request #25 from oerpub/ticket-423

mark block-image placeholder as ephemera while inserting - remove empty semantic blocks on cleanup