Fixed another flag in install script

.travis.yml

@@ -2,7 +2,7 @@ language: cpp
 before_install:
   - sudo add-apt-repository ppa:yjwong/gflags -y
   - sudo add-apt-repository ppa:h-rayflood/llvm -y
-  - sudo add-apt-repository ppa:ondrej/php5-5.6
+  - sudo add-apt-repository ppa:ondrej/php5-5.6 -y
   - sudo apt-get dist-upgrade -qq
   - sudo apt-get update -qq
   - sudo apt-get install -qq libgtest-dev libgflags-dev python-virtualenv clang-3.5 php5-dev