* proc: add tests for command-line arguments
adds tests to make sure command-line arguments are passed to Launch() properly
* proc_windows: pass command-line arguments to CreateProcess()
build command-line arguments according to how the standard library does it and pass the command line along to the actual syscall on Windows.
see discussion in #479
* proc: better testing of cmd-line arguments
* proc_windows: fix a possible error-case with passing just 1 argument
previously, the command line pointer passed to sys.CreateProcess was empty, if we had 0 parameters (len(cmd) == 1, as cmd[0] is the executable, so no cmdlineGo would be created, while with any argument it would as len(cmd) > 1). This might cause problems down the road, so make sure we include the command line every time, even if it seems to work without.
* proc: improve testing of command-line arguments
test that arguments with spaces are passed on correctly and DRY failure/success condition checking in the args test
