title: React Native activity class does not exist
body: <p>build.gradle file: </p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
  compileSdkVersion 23
  buildToolsVersion "22.0.1"
  
  defaultConfig {
      applicationId "com.fish"
      minSdkVersion 16
      targetSdkVersion 22
      versionCode 1
      versionName "1.0"
      ndk {
          abiFilters "armeabi-v7a", "x86"
      }
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
      }
  }
  }
  
  dependencies {
  compile fileTree(dir: 'libs', include: ['*.jar'])
  compile 'com.android.support:appcompat-v7:23.0.1'
  compile 'com.facebook.react:react-native:0.12.+'
  }
  </code></pre>
  
  <p>I tried many ways to fix this, but nothing seems to work. Maybe somebody got this error, too. I'm using node stable (4.0.0). </p>
  
  <p>Yesterday it worked(the app was opening with a white screen, but still it worked) but i don't know what happened meanwhile. </p>
  
  <p>L.e.: Sorry, i forgot to write the error :)</p>
  
  <pre><code>Starting the app (/Users/matei/Library/Android/sdk//platform-tools/adb shell am start -n com.fish/.MainActivity)...
  Starting: Intent { cmp=com.fish/.MainActivity }
  Error type 3
  Error: Activity class {com.fish/com.fish.MainActivity} does not exist.
  </code></pre>
  
  <p>I'm new to react native and I don't know what to do. </p>
  
  <p>L.e. 2: The project is the init one from react-native android command. Nothing added.</p>