Use https version of jcenter, as the http version has been dropped

build.gradle

@@ -16,7 +16,7 @@ if (!hasProperty('mainClass')) {
 repositories {
     mavenLocal()
     jcenter {
-        url "http://jcenter.bintray.com/"
+        url "https://jcenter.bintray.com/"
     }
     mavenCentral()
     maven {