title: Kotlin library 'rxkotlin-0.21.0.jar' has an unsupported format. Please update the library or the plugin
body: <p>The error in the title appears in Android Studio as a warning bar above all my code: <img src="https://i.stack.imgur.com/JVvo5.png" alt="Error"></p>
  
  <p>Android Studio version: <code>1.1.0</code><br>
  Kotlin plugin version for Android Studio: <code>0.11.91.AndroidStudio.4</code><br>
  <code>build.gradle</code> file that seems to be using all the most recent versions of the Kotlin libraries:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  apply plugin: 'kotlin-android'
  
  android {
      compileSdkVersion 22
      buildToolsVersion "22.0.1"
  
      defaultConfig {
          applicationId "ca.amandeep.simpletransit"
          minSdkVersion 16
          targetSdkVersion 22
          versionCode 1
          versionName "1.0"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
      sourceSets {
          main.java.srcDirs += 'src/main/kotlin'
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      compile 'com.android.support:appcompat-v7:22.0.0'
      compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
      compile 'com.squareup.retrofit:retrofit:1.9.0'
      compile('com.squareup.retrofit:converter-simplexml:1.9.0') {
          exclude module: 'stax'
          exclude module: 'stax-api'
          exclude module: 'xpp3'
      }
      compile 'com.squareup.okhttp:okhttp:2.3.0'
      compile 'com.squareup.okhttp:okhttp-urlconnection:2.3.0'
      compile 'com.google.guava:guava:18.0'
      compile 'com.facebook.stetho:stetho:1.0.1'
      compile 'com.facebook.stetho:stetho-okhttp:1.0.1'
      compile 'com.jakewharton.timber:timber:2.7.1'
      compile 'io.reactivex:rxkotlin:0.21.0'
      compile 'io.reactivex:rxandroid:0.24.0'
      compile 'com.github.techfreak:wizardpager:1.0.0'
  }
  buildscript {
      ext.kotlin_version = '0.11.91.1'
      repositories {
          mavenCentral()
      }
      dependencies {
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
          classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
          classpath 'com.jakewharton.hugo:hugo-plugin:1.2.1'
      }
  }
  repositories {
      mavenCentral()
  }
  
  apply plugin: 'com.jakewharton.hugo'
  </code></pre>