Adding QuickSort

[DillonAd]

Issue: #2

• [x] Have you followed the guidelines in our Readme.md document?
• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• [x] Have you created tests for your algorithm?

If you can check all of the above, congrats! :sparkles:

Description:

QuickSort (PartitionSort) is a divide and conquer algorithm that utilizes a chosen pivot point to logically divide the arrays. Since the sort is done in place the space complexity is O(n log(n)). The worst case for time complexity is O(n^2), but the average is O(n log(n)).

[bashbers]

I only see the quicksorttests.cs file inside your commit. I assume something went wrong whilst pushing.

[DillonAd]

Sorry about that! I found and pushed up the implementation. No clue how I managed that... 😃