Require ticker for min fee - no wildcard

[alpe]

Is your feature request related to a problem? Please describe.
I can see the additional complexity that comes with it in the code and also the the uncertainty for a an end user in terms of actual tx costs.

Describe the solution you'd like
Fail fast in init phase when fee is set without a ticker.

Describe alternatives you've considered
As I don't know the history why we have the wildcard I must assume we may want to support a list of options like gaiad: Minimum gas prices to accept for transactions; Any fee in a tx must meet this minimum (e.g. 0.01photino;0.0001stake). the ; is the OR but a , would be AND.

[ethanfrey]

This is a very good cleanup related to #364

We can consider multiple fee tokens at a later date, but for the foreseeable future, the only known production user of weave is iov, and they will only allow iov tokens for fees. When there is a clear usecase and need, we can revisit the multiple fee-token alternative described above.

[ethanfrey]

This still needs to be done for the (static) FeeDecorator. DynamicFeeDecorator was already fixed