Click a Nerd
APPLE YOSEMITE TRUST CERTIFICATE
Shortly after Apple quit supporting Yosemite, the trust certificate in the keychain for half the websites on the internet quit working. I won't go into all the techno babble and my theories as to why Apple did that. All you need to know is you can still use Yosemite and Safari as is. Just download this certificate: here
Now open up keychain. Import the certificate and set it to override trust to "always trust". Now close keychain and reboot your MacBook. ((( BAM ))) problem solved.
If you want to see all the technical crap behind what happened look at this: here