Minor fixes as found by Checkstyle

src/main/java/fr/xephi/authme/api/API.java

@@ -23,6 +23,7 @@ import javax.inject.Inject;
  * @deprecated Use {@link NewAPI}
  */
 @Deprecated
+@SuppressWarnings({"checkstyle:AbbreviationAsWordInName"}) // Justification: Class name cannot be changed anymore
 public class API {
 
     private static AuthMe instance;

src/main/java/fr/xephi/authme/api/NewAPI.java

@@ -24,6 +24,7 @@ import java.util.List;
  * NewAPI authmeApi = AuthMe.getApi();
  * </code>
  */
+@SuppressWarnings({"checkstyle:AbbreviationAsWordInName"}) // Justification: Class name cannot be changed anymore
 public class NewAPI {
 
     private static NewAPI singleton;