Set BUILD_PYTHON_INTERFACE to OFF by default and set it manually ON in the CI

.travis.yml

@@ -5,6 +5,7 @@ env:
     - CTEST_PARALLEL_LEVEL=4
     - CTEST_OUTPUT_ON_FAILURE=1
     - CXX_FLAGS_DEBUG="-O1"
+    - BUILD_PYTHON_INTERFACE=ON
 
 matrix:
   include:
@@ -97,7 +98,7 @@ script:
   - cd build
 
   # Configure
-  - cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_CXX_FLAGS=-w -DCMAKE_CXX_FLAGS_DEBUG=${CXX_FLAGS_DEBUG} ..
+  - cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_CXX_FLAGS=-w -DCMAKE_CXX_FLAGS_DEBUG=${CXX_FLAGS_DEBUG} -DBUILD_PYTHON_INTERFACE=${BUILD_PYTHON_INTERFACE} ..
 
   # Build
   - make -j4

CMakeLists.txt

@@ -58,7 +58,7 @@ IF(APPLE)
   endif("${isSystemDir}" STREQUAL "-1")
 ENDIF(APPLE)
 
-OPTION(BUILD_PYTHON_INTERFACE "Build the python bindings" ON)
+OPTION(BUILD_PYTHON_INTERFACE "Build the python bindings" OFF)
 
 # Tell CMake that we compute the PROJECT_VERSION manually.
 CMAKE_POLICY(SET CMP0048 OLD)