Initial attempt at moving travis to containerized infrastructure.

.travis.yml

 language: cpp
-
+sudo: false
+cache:
+  - ccache
 compiler:
  - clang
  - gcc
 
+addons: {apt: {packages: &default_packages [cmake, valgrind, doxygen]}}
 env:
   matrix:
     - CONF=debug   ARCH=x86_64
@@ -11,31 +14,35 @@ env:
     - CONF=debug   ARCH=x86
     - CONF=release ARCH=x86
   global:
+    - USE_CCACHE=1
+    - CCACHE_SLOPPINESS=pch_defines,time_macros
+    - CCACHE_COMPRESS=1
+    - CCACHE_MAXSIZE=100M
     - ARCH_FLAGS_x86='-m32'        # #266: don't use SSE on 32-bit
     - ARCH_FLAGS_x86_64='-msse4.2' #       use SSE4.2 on 64-bit
     - GITHUB_REPO='miloyip/rapidjson'
     - secure: "HrsaCb+N66EG1HR+LWH1u51SjaJyRwJEDzqJGYMB7LJ/bfqb9mWKF1fLvZGk46W5t7TVaXRDD5KHFx9DPWvKn4gRUVkwTHEy262ah5ORh8M6n/6VVVajeV/AYt2C0sswdkDBDO4Xq+xy5gdw3G8s1A4Inbm73pUh+6vx+7ltBbk="
 
-before_install:
-  - sudo apt-get update -qq
-  - sudo apt-get install -qq cmake valgrind
-  - sudo apt-get --no-install-recommends install doxygen # Don't install LaTeX stuffs
-  - if [ "$ARCH" = "x86" ]; then sudo apt-get install -qq g++-multilib libc6-dbg:i386; fi
-  - if [ "$CC" = "gcc" ] && [ "$CONF" = "debug" ]; then sudo pip install cpp-coveralls; export GCOV_FLAGS='--coverage'; fi
-
-install: true
+matrix:
+  include:
+    env: CONF=debug   ARCH=x86
+    addons: {apt: {packages: [*default_packages, g++-multilib, libc6-dbg:i386]}}
+  include:
+    env: CONF=release ARCH=x86
+    addons: {apt: {packages: [*default_packages, g++-multilib, libc6-dbg:i386]}}
 
 before_script:
 #   hack to avoid Valgrind bug (https://bugs.kde.org/show_bug.cgi?id=326469),
 #   exposed by merging PR#163 (using -march=native)
+    - if [ "$CC" = "gcc" ] && [ "$CONF" = "debug" ]; then export GCOV_FLAGS='--coverage'; fi
     - sed -i "s/-march=native//" CMakeLists.txt
-    - mkdir build 
+    - mkdir build
     - >
         eval "ARCH_FLAGS=\${ARCH_FLAGS_${ARCH}}" ;
-        (cd build && cmake 
+        (cd build && cmake
         -DRAPIDJSON_HAS_STDSTRING=ON
-        -DCMAKE_VERBOSE_MAKEFILE=ON 
-        -DCMAKE_BUILD_TYPE=$CONF 
+        -DCMAKE_VERBOSE_MAKEFILE=ON
+        -DCMAKE_BUILD_TYPE=$CONF
         -DCMAKE_CXX_FLAGS="$ARCH_FLAGS $GCOV_FLAGS"
         -DCMAKE_EXE_LINKER_FLAGS=$GCOV_FLAGS
         ..)
@@ -48,4 +55,5 @@ script:
   - make travis_doc
 
 after_success:
-  - coveralls -r .. --gcov-options '\-lp' -e thirdparty -e example -e test -e build/CMakeFiles -e include/rapidjson/msinttypes -e include/rapidjson/internal/meta.h -e include/rapidjson/error/en.h
+  - if [ "$CC" = "gcc" ] && [ "$CONF" = "debug" ]; then pip install --user cpp-coveralls; fi
+  - if [ "$CC" = "gcc" ] && [ "$CONF" = "debug" ]; coveralls -r .. --gcov-options '\-lp' -e thirdparty -e example -e test -e build/CMakeFiles -e include/rapidjson/msinttypes -e include/rapidjson/internal/meta.h -e include/rapidjson/error/en.h; fi