Add test support for intermediate state changes

- Adding expectStateEntered and expectStateExited methods
  for testing state enter/exit in a given order. This gives
  on option to expect i.e. states via anonymous transitions.
- Fixes #154

docs/src/reference/asciidoc/index.adoc

@@ -11,6 +11,7 @@
 :core-jdbc-JdbcTemplate: http://docs.spring.io/spring/docs/{spring-version}/spring-framework-reference/html/jdbc.html#jdbc-JdbcTemplate
 :sm-statecontext: http://docs.spring.io/spring-statemachine/docs/{spring-statemachine-version}/api/org/springframework/statemachine/StateContext.html
 :sm-statecontext-stage: http://docs.spring.io/spring-statemachine/docs/{spring-statemachine-version}/api/org/springframework/statemachine/StateContext.Stage.html
+:sm-statemachinetestplanbuilder-statemachinetestplanstepbuilder: http://docs.spring.io/spring-statemachine/docs/{spring-statemachine-version}/api/org/springframework/statemachine/test/StateMachineTestPlanBuilder.StateMachineTestPlanStepBuilder.html
 :spring-security-site: http://projects.spring.io/spring-security
 
 = Spring Statemachine - Reference Documentation

docs/src/reference/asciidoc/sm.adoc

@@ -1532,3 +1532,9 @@ These utilities are also used within a framework to test distributed
 state machine features and multiple machines can be added to a plan.
 If multiple machines are added then it is also possible to choose if
 event is sent to particular, random or all machines.
+
+[TIP]
+====
+All possible options for expected are documented in javadocs
+{sm-statemachinetestplanbuilder-statemachinetestplanstepbuilder}[_StateMachineTestPlanStepBuilder_].
+====