Simplify creating links against @BasePathAware controllers outside of SDR [DATAREST-1423]

Greg Turnquist opened DATAREST-1423 and commented

In Spring HATEAOS Examples (https://github.com/spring-projects/spring-hateoas-examples/blob/master/spring-hateoas-and-spring-data-rest/src/main/java/org/springframework/hateoas/examples/OrderProcessor.java#L88-L101), to create a custom endpoint using @BasePathAwareController, it requires extra handling to insert the basePath into the whole URI, like this:

private static Link applyBasePath(Link link, String basePath) {

	URI uri = link.toUri();

	URI newUri = null;
	try {
		newUri = new URI(uri.getScheme(), uri.getUserInfo(), uri.getHost(), //
				uri.getPort(), basePath + uri.getPath(), uri.getQuery(), uri.getFragment());
	} catch (URISyntaxException e) {
		e.printStackTrace();
	}

	return new Link(newUri.toString(), link.getRel());
}

Some form of utility, whether its a LinkBuilder or something else would make it easier for users to mesh custom controllers with SDR's controllers

Referenced from: commits https://github.com/spring-projects/spring-data-rest/commit/b527d323e0cec0ad8287da0410dfde32498d792e, https://github.com/spring-projects/spring-data-rest/commit/b1987411f3223aef446962c36935abb7057030f7