Update Changelog for 2.10.7

Changelog

+2.10.7: 2020-05-25
+   * Bugfix: Handle VM templates deleted in OpenNebula but VM instances still existing (MR!736)
+   Notes for deployment:
+   When deploying define a UPDATED_TEMPLATES string represented dictionary value in .env
+```
+   # Represents Template Ids that were
+   # deleted and the new template Id to look for the template
+   # definition
+   UPDATED_TEMPLATES="{1: 100}"
+```
 2.10.6: 2020-03-25
    * Bugfix: Handle Nonetype for discount's name (MR!735)
 2.10.5: 2020-03-17