Fix reverseArray and Fix abbreviateMiddleName

[AkshayIyer12]

Closes #528 Closes #764

• [x] Running yarn lint does not trigger any linter errors
• [x] The test of the method you have fixed is passing
• [x] You have written a new skeleton method for someone else to work on!
• [x] You have written tests to accompany your skeleton method

[AkshayIyer12]

@BlakeGuilloud It was a very good learning experience contributing to project and creating a new problem function for a new contributor.