Updated buildscript

Now publishes sources jar to local maven using newer 'maven-publish' plugin. Fixes an issue with IDEA's download sources when installing the library locally.

build.gradle

@@ -1,6 +1,6 @@
 plugins {
     id 'java'
-    id 'maven'
+    id 'maven-publish'
 }
 
 sourceCompatibility = JavaVersion.VERSION_1_8
@@ -12,4 +12,20 @@ version = '1.0.0'
 
 dependencies {
     compile files("${System.properties['java.home']}/../lib/tools.jar")
+}
+
+task sourceJar(type: Jar) {
+    from sourceSets.main.allJava
+}
+
+publishing {
+    publications {
+        mavenJava(MavenPublication) {
+            from components.java
+
+            artifact sourceJar {
+                classifier "sources"
+            }
+        }
+    }
 }