adding windows compatibility

[ghost]

Based on the work from #55 I created a pull request that addresses several Windows compatibility issues in the code and dpnishant's concern about regression failures in *nix platforms. It does the following things:

1. Uses the Python platform module to determine the OS and call time.strftime appropriately. On non-windows systems it uses the old call.
2. Changes all hardcoded "/"s in paths to use either os.sep, or os.path.join
3. Uses the Python tempfile module to replace the hardcoded reference to "/tmp"

I tested this on Windows 10 and MacOS 10.11.6 successfully, using the following launch parameters: -a iGoat -p ios -s scripts/iOS --spawn 1

[dpnishant]

@cutler-scott-ey Thanks for the PR. Appreciate it.