fix checkstyle line separator to lf (#219)

Author: jetersen

checkstyle.xml

@@ -2,7 +2,9 @@
 <!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.2//EN" "http://www.puppycrawl.com/dtds/configuration_1_2.dtd">
 <module name="Checker">
     <module name="FileTabCharacter" />
-    <module name="NewlineAtEndOfFile" />
+    <module name="NewlineAtEndOfFile">
+        <property name="lineSeparator" value="lf" />
+    </module>
     <module name="RegexpSingleline">
         <property name="format" value="\s+$"/>
         <property name="message" value="Trailing spaces are not allowed."/>