Add signin component.

src/main/java/org/codiki/account/AccountController.java

@@ -76,8 +76,8 @@ public class AccountController {
 	}
 	
 	@PostMapping("/signin")
-	public UserDTO signin(@RequestBody final UserDTO pUser, final HttpServletResponse pResponse) throws IOException {
-		return accountService.signin(pUser, pResponse);
+	public void signin(@RequestBody final User pUser, final HttpServletResponse pResponse) throws IOException {
+		accountService.signin(pUser, pResponse);
 	}
 	
 	@PutMapping("/")

src/main/java/org/codiki/account/AccountService.java

@@ -112,22 +112,20 @@ public class AccountService {
 		return result;
 	}
 
-	public UserDTO signin(final UserDTO pUser, final HttpServletResponse pResponse) throws IOException {
-		User user = new User();
-		
+	public void signin(final User pUser, final HttpServletResponse pResponse) throws IOException {
 		if(pUser.getName() == null || pUser.getEmail() == null || pUser.getPassword() == null || "".equals(pUser.getPassword().trim())) {
 			pResponse.sendError(HttpServletResponse.SC_BAD_REQUEST);
 		} else if(userRepository.findByEmail(pUser.getEmail()).isPresent()) {
 			pResponse.sendError(HttpServletResponse.SC_CONFLICT);
 		} else {
+			User user = new User();
+
 			user.setName(pUser.getName());
 			user.setEmail(pUser.getEmail());
 			user.setPassword(StringUtils.hashPassword(pUser.getPassword()));
 			user.setInscriptionDate(new Date());
 			userRepository.save(user);
 		}
-		
-		return new UserDTO(user);
 	}
 	
 	public void updateUser(final UserDTO pUser, final HttpServletRequest pRequest,