Release v0.0.26

Get prefix from Contact everywhere grpc_client is used

Contact wraps the standard Cosmos gRPC functions, but we also use
several query endpoints that are Gravity specific using a raw query
client. Because of that we don't bundle a prefix and have to pass one
around like we do in this commit.

In the future we should provide a Gravity Query Client wrapper that
wraps the prefix to be cleaner. In the medium term we should also be
able to request this value from the chain and stop passing it around at
all.