Added CEX.IO
CEX.IO changes
Merge pull request #813 from juliacex/cex

Added CEX.IO
HTTPSify Doc Links and Website Links for Finance

Changed the following to be HTTPS:
Fidelity Doc Link
OptionsHouse Doc Link
Vanguard Website Link

I tested all of the above to make sure they worked and no mixed content errors were given.

Charles Schwab's doc link was not made HTTPS, because their website gave mixed content rules.
Merge pull request #827 from jamcat22/patch-3

HTTPSify Doc Links and Website Links for Finance