Report db.sqlite3 size on dashboard

[tcely]

This does what I set out to do, but I'm not sure I like it.

Possibly make a function to get the size then pretty print it.

It does what it says on the tin, so it may as well get merged like this.

[meeb]

No objection to this, but probably might be nicer to use the database connection and check the vendor that's being used:

>>> from django.db import connection
>>> connection.vendor
'sqlite'

Using the database from the connection parameters might be cleaner too:

>>> connection.get_connection_params()['database']
'/home/some/path/to/a/db.sqlite3'

[tcely]

Those are good suggestions. I'll look into improving this.

[meeb]

Looks nicer, you happy for this to be merged?

[tcely]

Yeah. filesizeformat needs to be fixed to use proper prefixes, but that can happen later.