Package checkstyle module's jar in Eclipse plugin

See gh-179

Author: Lorenzo Dee

spring-javaformat-eclipse/io.spring.javaformat.eclipse/build.properties

@@ -4,6 +4,6 @@ bin.includes = META-INF/,\
                plugin.xml,\
                lifecycle-mapping-metadata.xml,\
                lib/spring-javaformat-formatter-eclipse.jar,\
-               lib/spring-javaformat-formatter.jar,
+               lib/spring-javaformat-formatter.jar,\
                lib/spring-javaformat-checkstyle.jar