Add new washer sample

- This sample demonstrate a use of history state

spring-statemachine-samples/washer/.gitignore

@@ -0,0 +1,19 @@
+.gradle
+bin
+build
+.settings
+.classpath
+.springBeans
+.project
+*.iml
+*.ipr
+*.iws
+metastore_db
+/samples/pig-scripting/src/main/resources/ml-100k.zip
+/samples/pig-scripting/src/main/resources/ml-100k/u.data
+/src/test/resources/s3.properties
+/.idea/
+.DS_Store
+/out/
+target
+*.log