BUILD: Update the Travis CI config to use the Trusty worker

.travis.yml

@@ -1,3 +1,6 @@
+sudo: required
+dist: trusty
+
 language: cpp
 compiler:
   - gcc
@@ -11,17 +14,26 @@ env:
    - coverity_scan_run_condition='"$CC" = gcc'
    - coverity_scan_script_test_mode=false
 
-before_script:
-  - echo "yes" | sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu trusty main universe restricted multiverse"
-  - sudo apt-get update -qq
-  - sudo apt-get -qq install libboost-all-dev libsdl2-dev libopenal-dev libfreetype6-dev libmad0-dev libfaad-dev libvorbis-dev libxvidcore-dev libgl1-mesa-dev zlib1g-dev liblzma-dev libxml2-dev
-
 script:
   - if [ "$COVERITY_SCAN_BRANCH" != 1 ]; then ./autogen.sh; fi
   - if [ "$COVERITY_SCAN_BRANCH" != 1 ]; then ./configure || cat config.log; fi
   - if [ "$COVERITY_SCAN_BRANCH" != 1 ]; then make -j4; fi
 
 addons:
+  apt:
+    packages:
+      - libboost-all-dev
+      - libsdl2-dev
+      - libopenal-dev
+      - libfreetype6-dev
+      - libmad0-dev
+      - libfaad-dev
+      - libvorbis-dev
+      - libxvidcore-dev
+      - libgl1-mesa-dev
+      - zlib1g-dev
+      - liblzma-dev
+      - libxml2-dev
   coverity_scan:
     build_script_url: https://raw.githubusercontent.com/$TRAVIS_REPO_SLUG/$TRAVIS_BRANCH/.travis_coverity.sh
     project: