added option for local build tasks

.gitignore

@@ -118,3 +118,5 @@ run/
 !gradle-wrapper.jar
 /gradlew
 /gradlew.bat
+
+local.gradle

build.gradle

@@ -47,3 +47,7 @@ shadowJar {
 
     mergeServiceFiles()
 }
+
+if (file("local.gradle").exists()) {
+    apply from: "local.gradle"
+}