Bump Gradle, Kotlin, and toml4j versions.

Apparently, Gradle was incompatible with Java 10, and neither was
toml4j.

fx/build.gradle

@@ -1,7 +1,7 @@
 apply plugin: 'application'
 
 dependencies {
-    compile 'com.moandjiezana.toml:toml4j:0.7.1'
+    compile 'com.moandjiezana.toml:toml4j:0.7.2'
     compile project(':core')
 }