It turns out defaultsDeep doesn't ever correctly combine Joi objects.
So, the only option is to use Joi's concat method to combine Joi
schemas. This complicates `getConfigForMethod`, but simplifies actual
route creation.
I ran into this because I'm setting up [lout](https://github.com/hapijs/lout)
on a server, and it requires properly formatted Joi schemas. This leads
me to believe there was something already wrong and Lout just exposed
the problem.
