Remove, not invalidate, Metadata on reload

Objects loaded over different class loaders are not the same. Nasty dragons lie here.

Also clean up the previous patch to no longer butcher imports.

Spigot-API-Patches/Add-MetadataStoreBase.removeAll-Plugin.patch

@@ -0,0 +1,39 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Tue, 16 Jul 2013 21:26:50 -0400
+Subject: [PATCH] Add MetadataStoreBase.removeAll(Plugin)
+
+So that on reload, metadata will be cleared
+
+diff --git a/src/main/java/org/bukkit/metadata/MetadataStoreBase.java b/src/main/java/org/bukkit/metadata/MetadataStoreBase.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/metadata/MetadataStoreBase.java
++++ b/src/main/java/org/bukkit/metadata/MetadataStoreBase.java
+@@ -0,0 +0,0 @@ public abstract class MetadataStoreBase<T> {
+     }
+ 
+     /**
++     * Removes all metadata in the metadata store that originates from the
++     * given plugin.
++     *
++     * @param owningPlugin the plugin requesting the invalidation.
++     * @throws IllegalArgumentException If plugin is null
++     */
++    public void removeAll(Plugin owningPlugin) {
++        Validate.notNull(owningPlugin, "Plugin cannot be null");
++        for (Iterator<Map<Plugin, MetadataValue>> iterator = metadataMap.values().iterator(); iterator.hasNext(); ) {
++            Map<Plugin, MetadataValue> values = iterator.next();
++            if (values.containsKey(owningPlugin)) {
++                values.remove(owningPlugin);
++            }
++            if (values.isEmpty()) {
++                iterator.remove();
++            }
++        }
++    }
++
++    /**
+      * Creates a unique name for the object receiving metadata by combining
+      * unique data from the subject with a metadataKey.
+      * <p>
+--