Update gradle wrapper and fix changelog task.

build.gradle

@@ -82,7 +82,8 @@ task changelog(type: JenkinsChangelog) {
     // skip if there is no forge jenkins pass
     onlyIf {
         project.hasProperty('forgeJenkinsPass')
-        project.file("build/distributions/${project.name}-${project.version}-changelog.txt").text = ""
+        // Not sure what abrar was trying to do here...
+        //project.file("build/distributions/${project.name}-${project.version}-changelog.txt").text = ""
     }
 
     outputs.upToDateWhen { false } // never up to date

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.4-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.5-bin.zip