Add search engine.

src/main/java/org/codiki/posts/PostController.java

@@ -54,7 +54,9 @@ public class PostController {
 	public PostDTO getByKey(@PathVariable("postKey") final String pPostKey, 
 			final HttpServletResponse response) {
 		final PostDTO result = getByKeyAndSource(pPostKey, response);
-		result.setText(parserService.parse(result.getText()));
+		if(result != null) {
+			result.setText(parserService.parse(result.getText()));
+		}
 		return result;
 	}
 	
@@ -79,10 +81,9 @@ public class PostController {
 				.map(PostDTO::new).collect(Collectors.toList());
 	}
 	
-	@PostMapping("/search")
-	public List<Post> search() {
-		// TODO
-		return null;
+	@GetMapping("/search/{searchCriteria}")
+	public List<PostDTO> search(@PathVariable("searchCriteria") final String pSearchCriteria) {
+		return postService.search(pSearchCriteria);
 	}
 	
 	@GetMapping("/byCategory/{categoryId}")