checks/cs50/2019/x/finance/check50/lookup.py (Handle lower case symbol)

[napitts]

lookup.py

• IEX API will accept lower case symbols.
• Student may choose to convert form input to lower case for consitency, prior to calling lookup() or storing in the database
• This creates an issue when using check50, but not when using regular IEX API

Recommend to change lookup.py to better mimic IEX API, such as:
if (symbol.upper() == "AAAA"):