Added Finding Exponent Program (#2238)

* Finding Exponent Program

* Build Error Fix - 1

* Build Error Fix - 2

* Error Fix - 1 datatype

* self-documenting naming convension added

* Update and rename exponent_recursion.py to power_using_recursion.py

* Fix typo

* Fix typo

Co-authored-by: Christian Clauss <cclauss@me.com>