"error: ‘UMatData’ does not name a type" when building Python wrapper with OpenCV 2.4.8

**Describe the bug**

When I attempt to build bgslibrary with a python wrapper, `make` terminates in error, seeming to complain of not finding a certain type definition which is perhaps absent from OpenCV 2 but not OpenCV 3. (I am using OpenCV 2. I can successfully build the library without a python error.)

**To Reproduce**

Using OpenCV 2.4.8 and Python 2.7.6 and Ubuntu 14.04.5 LTS and GCC 4.9.4, follow the instructions for [building bgslibrary with anaconda python](https://github.com/andrewssobral/bgslibrary/wiki/Wrapper:-Python#building-with-anaconda-python):

```
conda install boost
git clone --recursive https://github.com/andrewssobral/bgslibrary.git
cd bgslibrary/build
cmake -D BGS_PYTHON_SUPPORT=ON ..
make -j8
```

`make` terminates with an exit code of 2. Many an error is printed; the first of which is as follows, and many others are similar:

```
/home/myuser/Downloads/bgslibrary/wrapper_python/ndarray_converter.cpp:92:5: error: ‘UMatData’ does not name a type
UMatData* allocate(PyObject* o, int dims, const int* sizes, int type, size_t* step) const
```

**Expected behavior**

`make` should produce a bgslibrary library and a python wrapper. (The library, at least appears to be created: `libbgslibrary_core.so`.)

### System information
**Desktop (please complete the following information):**
- **OS Platform and Distribution (e.g., Linux Ubuntu 16.04)**: Linux Ubuntu 14.04.5 LTS
- **Python version (for issues related to the python wrapper)**: Python 3.6.6
- OpenCV 2.4.8
- GCC 4.9.4