Started adding tests

Added tests for the utils module and added a list of tests for the
command module.
Added test for the Command class.

Added the single_positional_test command test.
Added test for the Command class

Added the test for multiple positional arguments and fixed an issue that
it exposed.
Added tests for the Command class

Added the missing_potential_argument_test and the
extra_positional_argument_test and fixed the problems that it exposed.