add test with clang-format-3.4

Author: rhysd

.travis.yml

@@ -1,12 +1,15 @@
 language: ruby
 rvm:
-  - 1.9.3
+    - 1.9.3
 script: rake ci
+env:
+    - CLANG_VERSION="3.4"
+    - CLANG_VERSION="3.5"
 install:
     - wget -O - http://llvm.org/apt/llvm-snapshot.gpg.key | sudo apt-key add -
     - sudo echo 'deb http://llvm.org/apt/precise/ llvm-toolchain-precise main' > llvm.list
     - sudo echo 'deb-src http://llvm.org/apt/precise/ llvm-toolchain-precise main' >> llvm.list
     - sudo mv llvm.list /etc/apt/sources.list.d/
     - sudo apt-get -qq update
-    - sudo apt-get -qq --force-yes install clang-format-3.5
+    - sudo apt-get -qq --force-yes install clang-format-${CLANG_VERSION}
     - bundle install