THRIFT-3515 Python 2.6 compatibility and test on CI

This closes #766
diff --git a/.travis.yml b/.travis.yml
index 97440f3..88e9745 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -113,6 +113,12 @@
       BUILD_ENV="-e CC=gcc -e CXX=g++"
       DISTRO=centos
 
+    - TEST_NAME="Python 2.6 (CentOS 6)"
+      BUILD_CMD="../cmake.sh"
+      BUILD_ARG="-DWITH_PYTHON=ON -DWITH_CPP=OFF -DWITH_JAVA=OFF -DWITH_HASKELL=OFF"
+      BUILD_ENV="-e CC=gcc -e CXX=g++"
+      DISTRO=centos6
+
     # Distribution
     - TEST_NAME="make dist"
       BUILD_CMD="../make-dist.sh"