Force xcpretty 0.2.2 instead of new 0.2.3 release that is failing on Travis.

Author: appleguy

.travis.yml

@@ -10,7 +10,7 @@ before_install:
   - brew outdated xctool || brew upgrade xctool
   - brew outdated carthage || brew upgrade carthage
   - gem install cocoapods -v 1.0.1
-  - gem install xcpretty
+  - gem install xcpretty -v 0.2.2
   - gem install xcpretty-travis-formatter
 #  - gem install slather
   - xcrun simctl list