title: "Gradle files have changed since last project sync." message always shows up
body: <p>I'm working on an Android Studio project of which I write while constantly move back and forth from laptop to desktop using usb stick. There has been no problem for couple of months I tried this since Android Studio went stable, until today this message keeps showing up no matter how many times I sync the gradle:</p>
  
  <blockquote>
    <p>Gradle files have changed since last project sync. A project sync may be necessary for the IDE to work properly.</p>
  </blockquote>
  
  <p>Gradle Console indicates that the build is successful. I also tried cleaning and rebuilding the project, even reinstalling Android Studio, still the message pops out.</p>
  
  <p>What seems to be the problem? Is it not recommended to write a project on multiple Android Studios?</p>
  
  <p>Here's a look of my build.gradle:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
  compileSdkVersion 21
  buildToolsVersion "21.1.2"
  
  defaultConfig {
      applicationId "com.simplifyinc.prodigy"
      minSdkVersion 16
      targetSdkVersion 21
      versionCode 1
      versionName "0.3.2"
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      compile 'com.android.support:appcompat-v7:21.0.3'
      compile 'de.hdodenhof:circleimageview:1.2.1'
      compile 'com.oguzdev:CircularFloatingActionMenu:1.0.2'
      compile 'net.the4thdimension:audio-wife:1.0.3'
      compile project('libraries:android-crop')
  }
  </code></pre>