Move checkstyle configuration into sdk/ directory

Author: davorbonaci

pom.xml

@@ -126,8 +126,8 @@
             </dependency>
           </dependencies>
           <configuration>
-            <configLocation>checkstyle.xml</configLocation>
-            <suppressionsLocation>suppressions.xml</suppressionsLocation>
+            <configLocation>sdk/checkstyle.xml</configLocation>
+            <suppressionsLocation>sdk/suppressions.xml</suppressionsLocation>
             <consoleOutput>true</consoleOutput>
             <failOnViolation>true</failOnViolation>
             <includeResources>true</includeResources>

checkstyle.xml sdk/checkstyle.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-  ~ Copyright (C) 2015 Google Inc.
+  ~ Copyright (C) 2017 Google Inc.
   ~
   ~ Licensed under the Apache License, Version 2.0 (the "License"); you may not
   ~ use this file except in compliance with the License. You may obtain a copy of
@@ -30,7 +30,7 @@ page at http://checkstyle.sourceforge.net/config.html -->
       notice, so that this required text appears on the second line:
       <pre>
         /*
-         * Copyright 2015 Google Inc.
+         * Copyright 2017 Google Inc.
          *
          * (details of open-source license...)
       </pre>

suppressions.xml sdk/suppressions.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-  ~ Copyright (C) 2015 Google Inc.
+  ~ Copyright (C) 2017 Google Inc.
   ~
   ~ Licensed under the Apache License, Version 2.0 (the "License"); you may not
   ~ use this file except in compliance with the License. You may obtain a copy of