Store the workbooks being edited inside sqlite database of Horizon
django app. Now it's possible to:
* create a workbook;
* see it in the list of workbooks;
* edit it;
* delete it.
To use the models.py DATABASES variable in openstack_dashboard
settings needs to be set at least to sqlite3.
Change-Id: I9d4c013470e0fc13ef65484c8f6fae69cdad0a05
Implements: blueprint mistral-server-integration
Timur Sufiev