Add keys to .gitignore

[mdavis1982]

This PR adds the oauth keys to the .gitignore file if they don't already exist in it. This helps to prevent accidentally committing the keys to VCS.

[morloderex]

@mdavis1982 The idea here is fine but the implimentation doesn't scale.
Forexample this prevents the package from beeing used by people without the grep or echo commands command avaliable to them.

[mdavis1982]

@morloderex I'm not sure there's a supported system that doesn't have grep installed by default. It's certainly available on Linux and OS X, and the command will fail on Windows anyway because OpenSSL won't be installed by default.

[maximebeaudoin]

#33 sounds a better solution IMO.

[taylorotwell]

Closing because of issues raised in thread.