Migrate gradle scripts to have multiple modules and source sets. Using Kotlin-DSL for enhanced script debugging.

Signed-off-by: Gabriel Harris-Rouquette <gabizou@me.com>

sponge/build.gradle.kts

@@ -0,0 +1,30 @@
+buildscript {
+    repositories {
+        maven("https://repo.spongepowered.org/maven")
+    }
+}
+
+plugins {
+    java
+    id("org.spongepowered.plugin") version "0.9.0"
+}
+dependencies {
+    compile("org.spongepowered", "spongeapi", "7.1.0")  // SpongeAPI
+
+    implementation("org.bstats", "bstats-sponge", "1.4") // Sponge bstats
+}
+
+description = "mcMMO for Sponge"
+
+val compileJava by tasks.getting(JavaCompile::class) {
+    options.encoding = "UTF-8"
+}
+
+val jar by tasks.getting(Jar::class) {
+    manifest {
+        attributes(mapOf(
+                "Implementation-Title" to project.name,
+                "Implementation-Version" to project.version
+        ))
+    }
+}

sponge/src/main/java/com/gmail/nossr50/SpongePlugin.java

@@ -0,0 +1,22 @@
+package com.gmail.nossr50;
+
+import org.spongepowered.api.event.Listener;
+import org.spongepowered.api.event.game.state.GamePreInitializationEvent;
+import org.spongepowered.api.plugin.Plugin;
+
+@Plugin(
+    id = "mcmmo",
+    authors = {"nossr50", "gabizou", "bloodmage"},
+    version = "2.2.0-SNAPSHOT",
+    name = "mcMMO",
+    url = "https://www.mcmmo.org/"
+)
+public class SpongePlugin {
+
+
+    @Listener
+    public void onGamePreInit(GamePreInitializationEvent event) {
+
+    }
+
+}