Added format rule for CheckStyle

Author: brownian-motion

checkstyle.xml

@@ -8,4 +8,16 @@
         <!-- Report on each line in each file -->
         <property name="eachLine" value="true"/>
     </module>
+
+    <module name="TreeWalker">
+        <!-- Checks that the indentation style in this project is uniformly "2 spaces". -->
+        <module name="Indentation">
+            <property name="basicOffset" value="2"/>
+            <property name="braceAdjustment" value="0"/>
+            <property name="caseIndent" value="2"/>
+            <property name="throwsIndent" value="4"/>
+            <property name="lineWrappingIndentation" value="4"/>
+            <property name="arrayInitIndent" value="2"/>
+        </module>
+    </module>
 </module>