Added file aliquot_sum.py (#1985)

* Added file aliquot_sum.py containing a function to find theo

* Added parameter type info to aliquot_sum.py

* Update maths/aliquot_sum.py

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

* Update maths/aliquot_sum.py

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

* Updated code to raise ValueErrors if input is bad

* Fixed logical operators

* Removed unnecessary import

* Updated aliquot_sum.py

* fixed formatting

* fixed documentation

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