Fix addon specification.

Reduced build matrix.

.travis.yml

@@ -8,53 +8,29 @@ matrix:
       addons:
         apt:
           sources:
+            - sourceline: 'ppa:kzemek/boost'
             - ubuntu-toolchain-r-test
           packages:
             - g++-4.9
       env: COMPILER=g++-4.9
-    - compiler: gcc
-      addons:
-        apt:
-          sources:
-            - ubuntu-toolchain-r-test
-          packages:
-            - g++-5
-      env: COMPILER=g++-5
     - compiler: clang
       addons:
         apt:
           sources:
+            - sourceline: 'ppa:kzemek/boost'
             - ubuntu-toolchain-r-test
             - llvm-toolchain-precise-3.6
           packages:
             - clang-3.6
       env: COMPILER=clang++-3.6
-    - compiler: clang
-      addons:
-        apt:
-          sources:
-            - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.7
-          packages:
-            - clang-3.7
-      env: COMPILER=clang++-3.7
 
 env:
   global:
     - TELEBOTXX_BUILD_TESTS=ON
     - TELEBOTXX_GENERATE_DOC=OFF
 
-addons:
-  apt:
-    sources:
-      - sourceline: 'ppa:kzemek/boost'
-    packages:
-      - libboost1.58-dev
-      - libboost-test1.58-dev
-      - libboost-system1.58-dev
-      - libcurl4-openssl-dev
-
 before_script:
+  - sudo apt-get install -y libboost1.58-dev libboost-test1.58-dev libboost-system1.58-dev libcurl4-openssl-dev
   - export CXX=$COMPILER
   - mkdir build
   - cd build