Add tests to update BNS cash configuration

[webmaster128]

Each module can have a Configuration object and a transaction type to update this. For cash this is

• Configuration
• UpdateConfigurationMsg

Looks like there is only one configuration that can be updated at the moment

[willclarktech]

@webmaster128 Is it definitely just unit tests for this issue or do we need to sort out encoding/decoding of a transaction?

[webmaster128]

@willclarktech sorry, unittests -> tests. There should be a test showing that Configuration can be updated. This requires encoding/decoding of the ConfigurationMsg and the new configuration object.

[willclarktech]

Waiting for app.Tx to be updated, probably in Weave 0.17.1.

[willclarktech]

@webmaster128 What's the current status of this issue. Should we add it to 1.0?

[webmaster128]

@willclarktech I'd not consider it a blocker for 1.0.0, but as far as I can see it is ready for development. I moved it to position 1 in the backlog

[willclarktech]

Blocked by https://github.com/iov-one/weave/issues/815 which is scheduled for post-MVP.