Pyworking Testing materials

First version is at https://github.com/pyvec/pyworking-materials/tree/master/180324_Testovani

Should we adapt it for here or not? There are already 2 lessons for testings. I don't want to introduce a third one without planning. Maybe spliting into multiple sections and combining those (i.e. betamax is a specific topic, it doesn't need to be part of MI-PYT's testing document directly).

The materials are bit like this horse at the end, but that can be solved given some time:

首先检查链接目录 pyworking-materials/180324_Testovani 中的第一个版本，并将其与现有的两节 testing 课程进行比较。决定应在此处调整材料、将其拆分为多个部分，还是不纳入；完成的标准是形成一致同意的计划并适当整合课程，其中包括对 Betamax 主题的决定。