Add CommandLineFlaggedArgumentsParser with tests

[MarkOates]

This class makes it easier to take command line arguments with flags (sometimes called switches), and parse them into usable strings for an application.

A typical command line string with flags might look like this:

./my_program_name -c ClassName -a named_arg_1 named_arg_2:'deafult_value' -m method_name method_named_arg:'default_value'

Using CommandLineFlaggedArgumentsParser, you could pull out the following data:

get_flagged_args("-a") // returns { { "named_arg_1", "named_arg_2:'deafult_value'" } }