Start building against Spring Framework 4.2.6 snapshots

See gh-5322

spring-boot-dependencies/pom.xml

@@ -128,7 +128,7 @@
 		<snakeyaml.version>1.16</snakeyaml.version>
 		<solr.version>4.10.4</solr.version>
 		<spock.version>1.0-groovy-2.4</spock.version>
-		<spring.version>4.2.5.RELEASE</spring.version>
+		<spring.version>4.2.6.BUILD-SNAPSHOT</spring.version>
 		<spring-amqp.version>1.5.5.RELEASE</spring-amqp.version>
 		<spring-cloud-connectors.version>1.2.2.RELEASE</spring-cloud-connectors.version>
 		<spring-batch.version>3.0.7.RELEASE</spring-batch.version>