added test files for diffs with leading ./
added unit test for diffs with leading ./
Added code to the process validation to generate the correct error when a diff contains a filename with leading ./
Removed last line 'Only in ./us: Skillet.txt' from test files
Added a unit test to ensure that the process validation code generates the correct error message for a diff that contains a filename with a leading ./, also fixed a bug in the test_do_mission_incorrect_with_leading_dot_slashunit test, the unit test still passed with the bug but was technically incorrect because the code would return the wrong error