Pipe does break the google font request

[iuliaL]

This is not true any more
https://github.com/ojdx/react-font-face/blob/develop/src/react-font-face.js#L48
This pipe at the end should be removed cause it does break the request now
see for yourself
https://fonts.googleapis.com/css?family=Exo|

consider adding googleFontImportString.slice(0, -1) here https://github.com/ojdx/react-font-face/blob/develop/src/react-font-face.js#L51

Thank you for the lib.
I've used it before until this issue arised.