Update some versions

buildSrc/src/main/kotlin/Versions.kt

@@ -13,11 +13,11 @@ object Versions {
 
     const val de_fayard_buildsrcversions_gradle_plugin: String = "0.3.2" 
 
-    const val javalin: String = "2.7.0" 
+    const val javalin: String = "2.8.0"
 
-    const val org_jetbrains_kotlin_jvm_gradle_plugin: String = "1.3.21" 
+    const val org_jetbrains_kotlin_jvm_gradle_plugin: String = "1.3.30"
 
-    const val org_jetbrains_kotlin: String = "1.3.21" 
+    const val org_jetbrains_kotlin: String = "1.3.30"
 
     const val slf4j_simple: String = "1.7.26" 
 
@@ -27,11 +27,11 @@ object Versions {
      *      ./gradle/wrapper/gradle-wrapper.properties
      */
     object Gradle {
-        const val runningVersion: String = "5.3"
+        const val runningVersion: String = "5.4"
 
-        const val currentVersion: String = "5.3"
+        const val currentVersion: String = "5.4"
 
-        const val nightlyVersion: String = "5.4-20190321000037+0000"
+        const val nightlyVersion: String = "5.5-20190424001143+0000"
 
         const val releaseCandidate: String = ""
     }

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.3.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.4-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists