@NonNull
    public static Single<Response> getRequest(final String uri, @Nullable final Parameters params, @Nullable final File cacheFile) {
        return request("GET", uri, params, null, cacheFile);
    }
GET HTTP request

@param uri       the URI to request
@param params    the parameters to add to the GET request
@param cacheFile the name of the file storing the cached resource, or null not to use one
@return a single with the HTTP response, or an IOException
main/src/main/java/cgeo/geocaching/network/Network.java