chore: update to xcode 10.2 (#222)

Author: elena-p

.travis.yml

@@ -12,7 +12,7 @@ matrix:
       os: osx
       env:
         - Webpack="iOS"
-      osx_image: xcode10.0
+      osx_image: xcode10.2
       language: node_js 
       node_js: "10"
       jdk: oraclejdk8
@@ -39,7 +39,7 @@ matrix:
       env: 
         - BuildiOS="12.0"
         - Xcode="10.0"
-      osx_image: xcode10.0
+      osx_image: xcode10.2
       language: node_js 
       node_js: "10"
       jdk: oraclejdk8
@@ -67,7 +67,7 @@ matrix:
       jdk: oraclejdk8
       env: 
         - iOS="UnitTests"
-      osx_image: xcode10.0
+      osx_image: xcode10.2
       before_script: pod repo update
       script: 
         - cd src && npm i && npm run tsc && npm run tslint && cd ../demo && tns build ios