Update .travis.yml

Author: radex

.travis.yml

@@ -1,7 +1,7 @@
 language: objective-c
 cache: cocoapods
 rvm: 2.2.2
-osx_image: xcode7.2
+osx_image: xcode8
 
 before_install:
 - gem install cocoapods
@@ -20,4 +20,4 @@ script:
 
 - set -o pipefail && xctool archive -archivePath 'Tests' -project SwiftyTimerTests/SwiftyTimerTests.xcodeproj -scheme 'SwiftyTimerTests' && Tests.xcarchive/Products/Applications/SwiftyTimerTests.app/Contents/MacOS/SwiftyTimerTests
 
-- pod lib lint
+- pod lib lint