title: useOldManifestMerger causes build error
body: <p>I'm trying to use this new feature available in the version 0.10.0 of the Gradle Plugin for Android. But I keep getting this error message:</p>
  
  <blockquote>
    <p>FAILURE: Build failed with an exception.</p>
    
    <p><ul>
    <li>What went wrong: Execution failed for task ':xxxxxx:processDebugManifest'.</p>
    
    <blockquote>
      <p>Manifest merger failed : uses-sdk:minSdkVersion 1 cannot be smaller than version 7 declared in library
      com.android.support:appcompat-v7:19.1.0</li>
      </ul></p>
    </blockquote>
  </blockquote>
  
  <p>Here's my build.gradle</p>
  
  <pre><code>apply plugin: 'android'
  
      android {
          compileSdkVersion 19
          buildToolsVersion '19.0.3'
          useOldManifestMerger false
  
          defaultConfig {
              minSdkVersion 9
              targetSdkVersion 19
          }
  
          buildTypes {
              release {
                  runProguard true
                  proguardFile 'proguard-zap.cfg'
                  signingConfig signingConfigs.release
                  debuggable false
                  zipAlign true
              }
              debug {
                  packageNameSuffix ".debug"
                  debuggable true
                  runProguard false
              }
          }
  
          compileOptions {
              sourceCompatibility JavaVersion.VERSION_1_7
              targetCompatibility JavaVersion.VERSION_1_7
          }
      }
  
      dependencies {
          compile fileTree(dir: 'libs')
          compile 'com.android.support:appcompat-v7:+'
          compile 'com.google.android.gms:play-services:+'
          compile 'com.google.code.gson:gson:+'
          androidTestCompile files('libs/espresso-1.1-bundled.jar')
      }
  </code></pre>
  
  <p>How do I solve this?</p>