Trying to clean up travis config file.

.travis.yml

-language: cpp
 
-packages: &gcc5_pkgs
-  - gcc-5
-  - g++-5
-  - libstdc++6
 
 matrix:
   include:
-    # build and run all tests
-    - compiler: gcc
+    ###################
+    - language: cpp
+      compiler: 
+        - gcc
+        - clang
+      os: linux
       env:
-        - GCC_VER=5
-        - ADDRESS_MODEL=64
-        - BUILD_SYSTEM=cmake
-        - PATH=$HOME/bin:$PATH
         - VARIANT=test
-      addons: &ao_gcc5
-        apt:
-          sources: 
-            - ubuntu-toolchain-r-test
-          packages: *gcc5_pkgs
-    # build all examples
-    - compiler: gcc
+
+    ###################
+    - language: cpp
+      compiler: 
+        - gcc
+      os: linux
       env:
-        - GCC_VER=5
-        - ADDRESS_MODEL=64
-        - BUILD_SYSTEM=cmake
-        - PATH=$HOME/bin:$PATH
         - VARIANT=examples
-      addons: *ao_gcc5
-    # build the python extension 
-    - compiler: gcc
+
+    ###################
+    - language: python
+      python:
+        - "2.7"
+        - "3.6"
+      os: linux
       env:
-        - GCC_VER=5
-        - ADDRESS_MODEL=64
-        - BUILD_SYSTEM=cmake
-        - PATH=$HOME/bin:$PATH
         - VARIANT=python-api
-      addons: &ao_gcc5
-        apt:
-          sources: 
-            - ubuntu-toolchain-r-test
-          packages: 
-            - *gcc5_pkgs
-    # build the python3 extension 
-    - compiler: gcc
-      env:
-        - GCC_VER=5
-        - ADDRESS_MODEL=64
-        - BUILD_SYSTEM=cmake
-        - PATH=$HOME/bin:$PATH
-        - VARIANT=python3-api
-      addons: &ao_gcc5
-        apt:
-          sources: 
-            - ubuntu-toolchain-r-test
-            - virtualenv
-          packages: 
-            - python3 
-            - python3-pip
-            - *gcc5_pkgs
-    - os: osx
+
+    ###################
+    - language: cpp
+      os: osx
       osx_image: xcode9.2
       env:
         - VARIANT=test
-        - PATH=$HOME/bin:$PATH
          
           
-cache:
-  directories:
-    - cmake
-
-before_install:
-  - dlib/travis/before-install.sh
-
-install:
-    - if [ "$CXX" == "g++" ]; then export CXX=g++-$GCC_VER; export CC=gcc-$GCC_VER; fi
-    - if [ "$CXX" == "clang++" ]; then export CXX=clang++-$CLANG_VER; export CC=clang-$CLANG_VER; fi
-
 script:
   - dlib/travis/build-and-test.sh
 
-
-#notifications:
-#  email:
-#    false