Add 19 pytest tests covering the report, resource check, coin processing, refunds, change, profit, make_coffee and the main loop. Add a tests package and put the project root on the pytest path. Doxygen output is clean. The repository description and topics were set on the git host. Closes #13 Closes #14 Closes #15 Closes #16 Closes #17 Task: MIL-003#1 Task: MIL-003#2 Task: MIL-003#3 Task: MIL-003#4 Task: MIL-003#5