Support multiple JVM, and Debian alternatives.

Add ability to customize which JVM is installed on Debian.
Additionally, configure alternatives on Debian.

manifests/config.pp

@@ -0,0 +1,17 @@
+# On Debian systems, if alternatives are set, manually assign them.
+class java::config ( ) {
+  case $::osfamily {
+    Debian: {
+      if $java::use_java_alternative != undef and $java::use_java_alternative_path != undef {
+        exec { 'update-java-alternatives':
+          path    => '/usr/bin:/usr/sbin:/bin:/sbin',
+          command => "update-java-alternatives --set ${java::use_java_alternative} --jre",
+          unless  => "test /etc/alternatives/java -ef '${java::use_java_alternative_path}'",
+        }
+      }
+    }
+    default: {
+      # Do nothing.
+    }
+  }
+}