Augment test matrix with C++11.

.travis.yml

@@ -10,17 +10,32 @@
 language: cpp
 
 env:
-- PYTHON=python
-- PYTHON=python3
+- PYTHON=python CCFLAGS=-std=c++98
+- PYTHON=python CCFLAGS=-std=c++11
+- PYTHON=python3 CCFLAGS=-std=c++98
+- PYTHON=python3 CCFLAGS=-std=c++11
 
 compiler:
-  - gcc
+- gcc
 
+
+addons:
+  apt:
+    sources:
+    - ubuntu-toolchain-r-test
+    packages:
+    - gcc-4.8
+    - g++-4.8
+    - clang
+    - python-dev python-pip
+    - python3-dev
+    - libboost-all-dev
+    
 before_install:
-  - sudo apt-get install -y python-dev python-pip
   - sudo pip install future
-  - sudo apt-get install -y python3-dev
-  - sudo apt-get install -y libboost-all-dev
+
+install:
+- if [ "$CXX" = "g++" ]; then export CXX="g++-4.8" CC="gcc-4.8"; fi
 
 script: scons config --python=$PYTHON && scons && scons test