Support for assignments numbered as sub-projects

[japplefield]

Some courses like EECS 370 provide multiple autograder autograder assignments for the same project number. Projects are identified using a number-letter combination (e.g. Project 1a). A search for "p1a" wouldn't necessarily return only Project 1a based on the current parsing methods. This is a special case that probably needs to be handled separately. Example project names are:

• Project 1a - LC-2K Assembler
• Project 1m - Assembly-Language Multiplication
• Project 1s - Behavioral Simulator
• Project 2a - LC-2K Advanced Assembler
• Project 2c - Assembly Language Combinatorics
• Project 2l - LC2K Linker

[awdeorio]

Definitely add these examples to the unit tests in test_matching.py