Fix mkdir

[Fl4m3Ph03n1x]

This is the follow up of my research on this ticket: #127
After smashing my head against a wall for several days, I think I finally figured it out.
The command was failing because of how cmd mkdir behaves, in that, it behaves different from the one in poewrshell.

By changing that 1 line of code to only create folders if they don't exist already, I was able to fix the issue while still mantaining backwards compatibility, which was one of my requirements.

You can see a MWE project using my forked branch of bakeware here:

• https://github.com/Fl4m3Ph03n1x/bake_test

Please let me know what you think, and merge when convenient.

[fhunleth]

Looks good to me. Thanks!

[Fl4m3Ph03n1x]

Given this PR merges a fix for an issue with the Makefile, could we please do a 0.2.3 release?
This way other users that wish to use this library won't have to go to the same debugging process I had, it will simply work.