Try to clean the derived data before running the tests. Also added codecov integration

Author: bpoplauschi

.travis.yml

@@ -33,6 +33,14 @@ script:
  - echo Build example
  - pod install --project-directory=Example
  - xcodebuild build -workspace SDWebImageWebPCoder.xcworkspace -scheme SDWebImageWebPCoderExample -sdk iphonesimulator -destination 'name=iPhone 6s' -configuration Debug | xcpretty -c
+ 
+ - echo Clean DerivedData
+ - mkdir DerivedData
+ - rm -rf ~/Library/Developer/Xcode/DerivedData
 
  - echo Run the tests
  - xcodebuild test -workspace SDWebImageWebPCoder.xcworkspace -scheme 'SDWebImageWebPCoderTests' -sdk iphonesimulator -destination 'name=iPhone 6s' -configuration Debug | xcpretty -c
+ - mv ~/Library/Developer/Xcode/DerivedData/ ./DerivedData/iOS
+
+after_success:
+ - bash <(curl -s https://codecov.io/bash) -D './DerivedData/iOS' -J '^SDWebImageWebPCoder$' -F 'iOS'