Parameterize cloud version

E.g.

mvn install -P spring-cloud.version=Brixton.RELEASE

configserver/pom.xml

@@ -22,7 +22,7 @@
 			<dependency>
 				<groupId>org.springframework.cloud</groupId>
 				<artifactId>spring-cloud-dependencies</artifactId>
-				<version>Brixton.BUILD-SNAPSHOT</version>
+				<version>${spring-cloud.version}</version>
 				<type>pom</type>
 				<scope>import</scope>
 			</dependency>
@@ -32,6 +32,7 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<java.version>1.7</java.version>
+		<spring-cloud.version>Brixton.BUILD-SNAPSHOT</spring-cloud.version>
 	</properties>
 
 	<dependencies>