Update .travis.yml

Author: miccol

.travis.yml

@@ -1,29 +1,21 @@
 sudo: required
-
 dist: trusty
 language: cpp
 
-cache:
-  ccache: true
-
 os:
   - linux
 
 compiler:
   - gcc
   - clang
 
- addons:
-  apt:
-    packages:
-      - build-essential
-      - freeglut3-dev
-  
-  before_script:
+before_install:
+  - sudo apt-get update && sudo apt-get --reinstall install -qq build-essential freeglut3-dev
+
+before_script:
   # Prepare build directory
   - mkdir -p build
 
-  
-  script:
+script:
   # Build BTpp
   - (cd build; cmake .. ;cmake --build . )