Add apache snapshot repository to quickstart archetype

Backport of fix on master by Hadrian Zbarcea <hadrian@apache.org>
diff --git a/usage/archetypes/quickstart/src/brooklyn-sample/pom.xml b/usage/archetypes/quickstart/src/brooklyn-sample/pom.xml
index 9536d83..aef48be 100644
--- a/usage/archetypes/quickstart/src/brooklyn-sample/pom.xml
+++ b/usage/archetypes/quickstart/src/brooklyn-sample/pom.xml
@@ -50,6 +50,17 @@
     <project.entry>com.acme.sample.brooklyn.SampleMain</project.entry>
   </properties>
 
+  <repositories>
+    <repository>
+      <id>apache.snapshots</id>
+      <name>Apache Snapshot Repository</name>
+      <url>http://repository.apache.org/snapshots</url>
+      <releases>
+        <enabled>false</enabled>
+      </releases>
+    </repository>
+  </repositories>
+
   <dependencies>
     <dependency>
       <!-- this pulls in all brooklyn entities and clouds;