Update Kotlin version and add dependency on coroutines.

build.gradle

@@ -1,5 +1,5 @@
 buildscript {
-    ext.kotlin_version = '1.1.3'
+    ext.kotlin_version = '1.1.4-3'
     ext.dokka_version = '0.9.15'
 
     repositories {
@@ -19,7 +19,7 @@ subprojects {
     apply plugin: 'org.jetbrains.dokka'
 
     repositories {
-        mavenCentral()
+        jcenter()
     }
 
     dependencies {

fx/build.gradle

@@ -2,7 +2,14 @@ apply plugin: 'application'
 
 dependencies {
     compile 'com.moandjiezana.toml:toml4j:0.7.1'
+    compile 'org.jetbrains.kotlinx:kotlinx-coroutines-core:0.18'
     compile project(':core')
 }
 
+kotlin {
+    experimental {
+        coroutines "enable"
+    }
+}
+
 mainClassName = 'org.nwapw.abacus.fx.AbacusApplication'