Investigate using python unittest/pytest library with python_raft

[TB-1993]

To further standardise the testing framework, it would be good to integrate it with an industry standard testing library. The two most standard libraries for testing with python are unittest and pyyaml. Below, I've started a list of pros and cons for each, but we will need to investigate the viability of integrating with each to decide which we use.

Unittest:

Pros:

• Standard library for python
• Class based
• Very widely used

Cons:

• Not very flexible
• Not easiest to learn

Pytest:

Pros:

• Very flexible with plugins for different outputs
• Simple to use

Cons:

• Not as widely used, so syntax isn't as standard
• Lack of class based tests may make integration more difficult
• Adds another non-standard library

[zghp]

Can use unittest for the testControl class and the tests cases and then run the tests using pytest (which will have an xml output as well)