Resize images of students and mentors to same ratio (#603)

[kksinghal]

• [x] Included a Preview link and screenshot showing after and before the changes.
• [x] Included a description of the change below.
• [x] Squashed the commits.

Changes done in this Pull Request

• Preview Link
• Fixes #603

Description / Changes

1. The unequal ratios of images was leading to spaces in students and mentors section .
2. Some images were not even visible due to different extension in image and src . So , fixed these .

Screenshots if any:

Before:

After:

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[rpotter12]

@KSNINJA your preview link is switching current page to your fork repo. Please provide a preview link of the site with your changes.

[kksinghal]

Earlier , I just made the ratio 1:1 , now I made a constant size for images to 240:240 pixels . You can review now .