Start building against Reactor Bom Aluminium snapshots for SR2

See gh-8589

spring-boot-dependencies/pom.xml

@@ -141,7 +141,7 @@
 		<netty.version>4.1.8.Final</netty.version>
 		<postgresql.version>9.4.1212.jre7</postgresql.version>
 		<querydsl.version>4.1.4</querydsl.version>
-		<reactor-bom.version>Aluminium-SR1</reactor-bom.version>
+		<reactor-bom.version>Aluminium-BUILD-SNAPSHOT</reactor-bom.version>
 		<rxjava.version>1.2.7</rxjava.version>
 		<rxjava-adapter.version>1.2.1</rxjava-adapter.version>
 		<rxjava2.version>2.0.7</rxjava2.version>