Added Java plugin loader + a plugin manager

By: Dinnerbone <dinnerbone@dinnerbone.com>

paper-api/src/org/bukkit/plugin/java/JavaPluginLoader.java

@@ -0,0 +1,37 @@
+
+package org.bukkit.plugin.java;
+
+import java.io.File;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.plugin.PluginLoader;
+import java.util.regex.Pattern;
+
+/**
+ * Represents a Java plugin loader, allowing plugins in the form of .jars
+ */
+public final class JavaPluginLoader implements PluginLoader {
+    private final Pattern[] fileFilters = new Pattern[] {
+        Pattern.compile("\\.jar$"),
+    };
+    
+    public Plugin getPlugin(String name) {
+        throw new UnsupportedOperationException("Not supported yet.");
+    }
+
+    public boolean isPluginEnabled(String name) {
+        throw new UnsupportedOperationException("Not supported yet.");
+    }
+
+    public boolean isPluginEnabled(Plugin plugin) {
+        throw new UnsupportedOperationException("Not supported yet.");
+    }
+
+    public Plugin loadPlugin(File file) {
+        throw new UnsupportedOperationException("Not supported yet.");
+    }
+
+    public Pattern[] getPluginFileFilters() {
+        return fileFilters;
+    }
+
+}