Added support for SVG files in the AztecCode.save method

[Zazzik1]

I added a new class SVGFactory, which allows to create SVG images based on the 2d matrix. The method SVGFactory.save is called in the AztecCode.save method if the file name ends with .svg. All of the code was covered by tests. Please find the example code below. The advantage of SVG is that it scales well without any loss of quality.

Unfortunately, I didn't add the option to provide text above the image, because we would need to attach heavy font files to each image (or provide links to fonts which is also not always possible). Also, I'm not sure if it would be possible to easily wrap long texts

py.test --verbose

test_aztec_code_generator.py::Test::test_find_optimal_sequence PASSED                                                            [ 12%]
test_aztec_code_generator.py::Test::test_get_data_codewords PASSED                                                               [ 25%]
test_aztec_code_generator.py::Test::test_optimal_sequence_to_bits PASSED                                                         [ 37%]
test_aztec_code_generator.py::Test::test_reed_solomon PASSED                                                                     [ 50%]
test_aztec_code_generator.py::TestSvgFactory::test_create_svg PASSED                                                             [ 62%]
test_aztec_code_generator.py::TestSvgFactory::test_init PASSED                                                                   [ 75%]
test_aztec_code_generator.py::TestSvgFactory::test_save PASSED                                                                   [ 87%]
test_aztec_code_generator.py::TestAztecCode::test_save_should_support_svg PASSED                                                 [100%]

========================================================== 8 passed in 0.09s ==========================================================

[Zazzik1]

Hi @dlenski, would you like to include this feature in your fork https://github.com/dlenski/aztec_code_generator and pypi? Should I open a new PR for it?