Fix/readme update (eugenp#1602)

* Add project for hibernate immutable article
Add Event entity
Add hibernate configuration file
Add hibernateutil for configuration
Add test to match snippets from article

* Update Readme for core-java and spring-hibernate4

* Updating repo

Author: Walter Gómez

core-java/README.md

@@ -11,6 +11,7 @@
 - [Converting between a List and a Set in Java](http://www.baeldung.com/convert-list-to-set-and-set-to-list)
 - [Convert a Map to an Array, List or Set in Java](http://www.baeldung.com/convert-map-values-to-array-list-set)
 - [Java – Write to File](http://www.baeldung.com/java-write-to-file)
+- [Java - Convert File to InputStream] (http://www.baeldung.com/convert-file-to-input-stream)
 - [Java Scanner](http://www.baeldung.com/java-scanner)
 - [Java Timer](http://www.baeldung.com/java-timer-and-timertask)
 - [Java – Byte Array to Writer](http://www.baeldung.com/java-convert-byte-array-to-writer)

spring-hibernate4/README.md

@@ -13,6 +13,7 @@
 - [Eager/Lazy Loading In Hibernate](http://www.baeldung.com/hibernate-lazy-eager-loading)
 - [Hibernate Criteria Queries](http://www.baeldung.com/hibernate-criteria-queries)
 - [Hibernate One to Many Annotation Tutorial](http://www.baeldung.com/hibernate-one-to-many)
+- [Guide to @Immutable Annotation in Hibernate](http://www.baeldung.com/hibernate-immutable)
 
 ### Quick Start