Invalid default database

To repro:

• Generate the default new database, with development settings
• Run the example experiment user/user/single/1/single
• Add that experiments to a (new) report
• Add a new plot/graph item to the report
• Click the Save Report button (top-right of the reports page)

Expected:

• The server saves the report with the new plot successfully

Actual:

• The server encounters an error and returns a 500
• Django encounters an error on line 201 of beat/web/reports/models.py, where value['selected_template'] is None, and one cannot call split() on None