Implemented facebook login auth feature

[siddaiahm]

-user can login through facebook account

[tima101]

@delgermurun @klyburke I wonder if we can have a new folder inside builderbook and/or saas repositories, with custom features like FB Login. What do you think?

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Alternatively, we can reject merging new features to this repo since we will not maintain them.

[klyburke]

@siddaiahm thanks for the contribution!

@tima101 I would go with a separate folder containing this code, note that it is an example from a contributor and not being actively maintained by us.

[tima101]

@siddaiahm Thank you for your contribution.

I haven't run your code but it looks good.

I created a new folder at the root of the repo: examples. You are welcome to contribute minimal working example to that folder.

The reason to put it in separate folder is because we will review but not maintain content of example folder.