If the user doesn't specify the connection on the tuskar config we throw an unhelpful error

[Dougal Matthews]

The error currently looks like this:

    $ tuskar-dbsync --config-file etc/tuskar/tuskar.conf.sample
    2014-08-21 10:51:05.636 31110 CRITICAL tuskar [-] AttributeError: 'NoneType' object has no attribute 'drivername'

The only thing you need to change in the sample config (at the moment) is the connection= parameter.

We should at least make the error a bit more self explanitory - this may be something that needs to be fixed in oslo.db