selection_sort.py Add Selection Sort Algo in Python

[aloks98]

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Fixes #446

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[TravisBuddy]

Hey @aloks98,
Your changes look good to me!

View build log

TravisBuddy Request Identifier: 697bf260-e4f2-11e9-950a-c74496fc22d4

[aloks98]

This adds SelectionSort Algorithm. The Selection Sort Algorithm sorts an array by repeatedly finding the minimum element (considering ascending order) from unsorted part and putting it at the beginning.

This fixes the issue #446