Support GeoPoint type

Description/Steps to reproduce

I'm attempting to start my project by using npm start and get the following output:

> project-api@1.0.0 prestart /Users/joris/Documents/Personal/Projects/project/project-api
> npm run build


> project-api@1.0.0 build /Users/joris/Documents/Personal/Projects/project/project-api
> lb-tsc es2017 --outDir dist


> project-api@1.0.0 start /Users/joris/Documents/Personal/Projects/project/project-api
> node .

Cannot start the application. Error: Unsupported type: geopoint
    at stringTypeToWrapper (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/repository-json-schema/dist/src/build-schema.js:68:19)
    at metaToJsonProperty (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/repository-json-schema/dist/src/build-schema.js:101:25)
    at modelToJsonSchema (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/repository-json-schema/dist/src/build-schema.js:151:32)
    at Object.getJsonSchema (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/repository-json-schema/dist/src/build-schema.js:22:27)
    at generateOpenAPISchema (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/openapi-v3/dist/src/controller-spec.js:181:49)
    at resolveControllerSpec (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/openapi-v3/dist/src/controller-spec.js:128:17)
    at Object.getControllerSpec (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/openapi-v3/dist/src/controller-spec.js:205:16)
    at RestServer._setupHandlerIfNeeded (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/rest/dist/src/rest.server.js:195:42)
    at RestServer.start (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/rest/dist/src/rest.server.js:498:14)
    at _forEachServer.s (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/core/dist/src/application.js:123:42)
    at Promise.all.bindings.map (/Users/joris/Documents/Personal/Projects/project/project-api/node_modules/@loopback/core/dist/src/application.js:145:26)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! project-api@1.0.0 start: `node .`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the project-api@1.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/joris/.npm/_logs/2018-11-05T15_06_38_766Z-debug.log

In one of my models, I have a property of type 'geopoint':

  @property({
    type: 'geopoint',
    required: true,
  })
  location: string;

Upon closer inspection, no case is defined for the 'geopoint' type in the switch statement in @loopback/repository-json-schema/dist/src/build-schema.js.

Expected result

For the Loopback 4 project to start.

Additional information

• node -e 'console.log(process.platform, process.arch, process.versions.node)' shows darwin x64 10.12.0
• npm ls --prod --depth 0 | grep loopback shows no output

Comienza con el switch de @loopback/repository-json-schema/dist/src/build-schema.js que informa de «Unsupported type: geopoint» y, a continuación, sigue cómo se genera el esquema a través de @loopback/openapi-v3. Ejecuta el escenario npm start indicado con un modelo que use una propiedad geopoint; se considera terminado cuando la aplicación se inicia sin ese error.