Update ios and android build version

Author: Zdravko Branzov

.travis.yml

@@ -17,26 +17,25 @@ matrix:
       os: linux
       node_js: "6"
       script: cd src && npm run ci.tslint && cd ../demo && npm run ci.tslint && cd ../demo-angular && npm run ci.tslint
-    - stage: "WebPack"
+    - stage: "WebPack and Build"
       os: osx
       env:
-        - Webpack="iOS"
-      osx_image: xcode8.3
+        - WebpackiOS="11"
+      osx_image: xcode9.1
       language: node_js 
       node_js: "6"
       jdk: oraclejdk8
       script: cd demo && npm run build.plugin && npm i && npm run ns-bundle --ios --build-app --uglify && cd ../demo-angular && npm run build.plugin && npm i && npm run ns-bundle --ios --build-app --uglify
     - language: android
       os: linux
       env:
-        - Webpack="Android"
+        - WebpackAndroid="26"
       jdk: oraclejdk8
       before_install: nvm install 6.10.3
       script: cd demo && npm run build.plugin && npm i && npm run ns-bundle --android --build-app --uglify --snapshot && cd ../demo-angular && npm run build.plugin && npm i && npm run ns-bundle --android --build-app --uglify --snapshot
-    - stage: "Build"
+    - language: android
       env: 
-        - BuildAndroid="25"
-      language: android
+        - BuildAndroid="26"
       os: linux
       jdk: oraclejdk8
       before_install: nvm install 6.10.3
@@ -45,9 +44,9 @@ matrix:
         - "curl -u $SAUCE_USER:$SAUCE_KEY -X POST -H 'Content-Type: application/octet-stream' $ANDROID_SAUCE_STORAGE --data-binary @$ANDROID_PACKAGE_FOLDER/$ANDROID_PACKAGE"
     - os: osx
       env: 
-        - BuildiOS="10.3"
-        - Xcode="8.3"
-      osx_image: xcode8.3
+        - BuildiOS="11"
+        - Xcode="9.1"
+      osx_image: xcode9.1
       language: node_js 
       node_js: "6"
       jdk: oraclejdk8
@@ -79,8 +78,9 @@ android:
   components:
     - tools
     - platform-tools
-    - build-tools-25.0.2
-    - android-25
+    - build-tools-26.0.1
+    - android-26
+    - android-23
     - extra-android-m2repository
 
 before_cache: