Set up our own FHIR server to serve requests for our fake patient in demo / integration tests

[fzhao99]

In the work for our super-sick patient, we ran into some issues that we think have to do with the reliability of Public HAPI. We might want to set up our own FHIR server for demo / test use to have more control over how quickly we can access these things over an API call.

[robertandremitchell]

As part of this work, we will likely want to also address the ability in demo-mode to click ahead on the SearchForm page without filling out specific fields. Right now, with the public server, clicking nothing advances.

Rather than address it as a separate ticket, I figured it made sense to fold that mini-bug into this work, since we will need to update that step anyway.