Run apt-get update

Author: mbinna

.travis.yml

@@ -3,13 +3,9 @@ language: cpp
 compiler:
     - clang
     - gcc
-addons:
-    apt:
-        sources:
-            - ubuntu-toolchain-r-test
-        package:
-            - cmake
-            - protobuf
+before_install:
+    - sudo apt-get -qq update
+    - sudo apt-get install -y cmake protobuf
 script:
     - mkdir build
     - cd build