Added Gaussian blurring method to augmentations

[sirish-gambhira]

Hey @kartikdutt18, kindly review this PR and let me know your suggestions/ comments on the method. I would be happy to work on them and improve the code.

[mlpack-bot[bot]]

Thanks for opening your first pull request in this repository! Someone will review it when they have a chance. In the mean time, please be sure that you've handled the following things, to make the review process quicker and easier:

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Thank you again for your contributions! :+1:

[mlpack-bot[bot]]

This issue has been automatically marked as stale because it has not had any recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions! :+1: