Add blob detection example on Python

[ihhub]

We have an example of Bitmap Operation which is made by @MatthewMcGonagle. We need to expand our Python module and example to cover more code of the library. We cannot ask to do a huge task to implement unit or performance tests initially so a small step as an implementation of existing example is reasonable. Original blob detection example made in C++ locates at examples/blob_detection directory.

[ngetahun]

I'll make a PR.

[ihhub]

Nice!