Replace the existing solver API end point.

As for the solver, I couldn't find the stuff Cam did to make it backwards compatible...maybe that got removed at some point? We can leave the existing one up, but I'd rather not make something look official if we're just going to eventually shift to hosting it at solver.PD (which I think makes sense). This isn't meant to be a "sibling project", but rather a complete rewrite of the existing one. So, for now, just go with hard-coded IP's to keep it looking unofficial, and create an issue assigned to me to have it folded into the current setup (requires a fair bit of server setup wrangling, so best to just let Nir & I take care of it).

- Please be aware the existing API is Synchronised and the PAAS is asynchronoused.
- Also, the deault output is not acceptable by Planning Editor website. Please remember to use the adaptor to parse the result.