Add dependency management for some additional Hibernate modules

hibernate-jpamodelgen was requested by a Boot user. hibernate-ehcache
and hibernate-envers were requested by a Spring IO Platform user (see
spring-io/platform#11

Closes gh-1896

spring-boot-dependencies/pom.xml

@@ -945,10 +945,25 @@
 				<artifactId>hamcrest-library</artifactId>
 				<version>${hamcrest.version}</version>
 			</dependency>
+			<dependency>
+				<groupId>org.hibernate</groupId>
+				<artifactId>hibernate-ehcache</artifactId>
+				<version>${hibernate.version}</version>
+			</dependency>
 			<dependency>
 				<groupId>org.hibernate</groupId>
 				<artifactId>hibernate-entitymanager</artifactId>
-				<version>${hibernate-entitymanager.version}</version>
+				<version>${hibernate.version}</version>
+			</dependency>
+			<dependency>
+				<groupId>org.hibernate</groupId>
+				<artifactId>hibernate-envers</artifactId>
+				<version>${hibernate.version}</version>
+			</dependency>
+			<dependency>
+				<groupId>org.hibernate</groupId>
+				<artifactId>hibernate-jpamodelgen</artifactId>
+				<version>${hibernate.version}</version>
 			</dependency>
 			<dependency>
 				<groupId>org.hibernate</groupId>