Add uiOptions setting to pass arbitrary options to Swagger UI

[markopy]

There are quite a few Swagger UI settings which someone using hapi-swagger might want to change. Instead of adding them all as plugin options this PR adds a single uiOptions setting which can be an object of arbitrary options passed to Swagger UI.

[robmcguinness]

@markopy would it be possible to add all the options in the type definition?

[markopy]

@robmcguinness Do you mean the Swagger UI options? The main point of this PR was to not have to explicitly define them all in hapi-swagger because it's a constant maintenance burden and the list will inevitably become out of date.

[robmcguinness]

Understood. Just trying to make the TS community happy 😄