Update travis configs.

.travis.yml

@@ -1,4 +1,10 @@
 language: objective-c
-osx_image: xcode7.1
+osx_image: xcode7.3
+notifications:
+  email:
+    on_success: never
 script:
     - xcodebuild clean test -workspace PainlessInjection/PainlessInjection.xcworkspace -scheme PainlessInjection -sdk iphonesimulator9.3 ONLY_ACTIVE_ARCH=NO | xcpretty
+
+after_success:
+    - pod lib lint --allow-warnings;