Travis: ANDROID_API_LEVEL back to 24

.travis.yml

@@ -10,7 +10,7 @@ cache:
 
 env:
   global:
-    - ANDROID_API_LEVEL=25
+    - ANDROID_API_LEVEL=24 # 25 Error: Invalid --abi armeabi-v7a for the selected target
     - ANDROID_BUILD_TOOLS_VERSION=25.0.2
     - ANDROID_ABI=armeabi-v7a
     - ADB_INSTALL_TIMEOUT=20 # minutes (2 minutes by default)
@@ -22,6 +22,7 @@ android:
     - tools # to install Android SDK tools 25.1.x, https://github.com/travis-ci/travis-ci/issues/6040#issuecomment-219367943
     - build-tools-$ANDROID_BUILD_TOOLS_VERSION
     - android-$ANDROID_API_LEVEL
+    - android-25
     # Support library
     - extra-android-support
     # Latest artifacts in local repository