Symbols with non-alphanumeric characters fail

[addisonlynch]

The following request will fail:

from iexfinance imort Stock

aig = Stock("aig+")

# iexfinance.utils.exceptions.IEXSymbolError: Symbol AIG+ not found.

per the IEX docs:

Be sure to url-encode the values you pass to your parameter.
(i.e. ?symbols=AIG+ encoded is ?symbols=AIG%2b.)

since we are not doing so now, we are essentially passing:

symbols=AIG+

which will not work. Need to url-encode all symbol names to force percent-encodings of non-alphanum characters.