Added travis config - prepare and check release build

.travis.yml

@@ -0,0 +1,43 @@
+language: android
+
+jdk:
+- oraclejdk8
+
+android:
+  components:
+  - tools
+  licenses:
+  - 'android-sdk-license-.+'
+
+before_install:
+- chmod +x gradlew
+# Install SDK license so Android Gradle plugin can install deps.
+- mkdir "$ANDROID_HOME/licenses" || true
+- echo "d56f5187479451eabf01fb78af6dfcb131a6481e" > "$ANDROID_HOME/licenses/android-sdk-license"
+# Install the rest of tools (e.g., avdmanager)
+- sdkmanager tools
+
+install:
+- ./gradlew clean assembleRelease --stacktrace
+
+script:
+- ./gradlew lintRelease testReleaseUnitTest --stacktrace
+
+branches:
+  except:
+  - gh-pages
+
+notifications:
+  email: false
+
+sudo: false
+
+before_cache:
+- rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
+- rm -fr $HOME/.gradle/caches/*/plugin-resolution/
+
+cache:
+  directories:
+  - $HOME/.gradle/caches/
+  - $HOME/.gradle/wrapper/
+  - $HOME/.android/build-cache

sample/build.gradle

@@ -20,6 +20,10 @@ android {
             signingConfig signingConfigs.debug
         }
     }
+
+    dexOptions {
+        preDexLibraries = properties.containsKey('android.injected.invoked.from.ide')
+    }
 }
 
 dependencies {