Update build tools for Android Studio 3.1

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=190896757

build.gradle

@@ -17,8 +17,8 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.1'
-        classpath 'com.novoda:bintray-release:0.8.0'
+        classpath 'com.android.tools.build:gradle:3.1.0'
+        classpath 'com.novoda:bintray-release:0.8.1'
     }
     // Workaround for the following test coverage issue. Remove when fixed:
     // https://code.google.com/p/android/issues/detail?id=226070

constants.gradle

@@ -22,7 +22,7 @@ project.ext {
     minSdkVersion = 14
     targetSdkVersion = 27
     compileSdkVersion = 27
-    buildToolsVersion = '26.0.2'
+    buildToolsVersion = '27.0.3'
     testSupportLibraryVersion = '0.5'
     supportLibraryVersion = '27.0.0'
     playServicesLibraryVersion = '11.4.2'

javadoc_combined.gradle

@@ -35,7 +35,6 @@ class CombinedJavadocPlugin implements Plugin<Project> {
           }
           exclude "**/BuildConfig.java"
           exclude "**/R.java"
-          destinationDir project.file("$project.buildDir/docs/javadoc")
           doLast {
             libraryModules.each { libraryModule ->
               project.copy {

publish.gradle

@@ -16,8 +16,8 @@ if (project.ext.has("exoplayerPublishEnabled")
     apply plugin: 'bintray-release'
     publish {
         artifactId = releaseArtifact
-        description = releaseDescription
-        version = releaseVersion
+        desc = releaseDescription
+        publishVersion = releaseVersion
         repoName = getBintrayRepo()
         userOrg = 'google'
         groupId = 'com.google.android.exoplayer'