add deps for Google Authenticator
add deps for Google Authenticator

* pyotp for computing two factor values
* qrcode for generating easily scannable qr codes for shared secrets

kelcecil/securedrop,ageis/securedrop,jeann2013/securedrop,chadmiller/securedrop,ehartsuyker/securedrop,chadmiller/securedrop,pwplus/securedrop,heartsucker/securedrop,jeann2013/securedrop,conorsch/securedrop,GabeIsman/securedrop,garrettr/securedrop,GabeIsman/securedrop,chadmiller/securedrop,chadmiller/securedrop,GabeIsman/securedrop,harlo/securedrop,garrettr/securedrop,heartsucker/securedrop,kelcecil/securedrop,heartsucker/securedrop,jrosco/securedrop,pwplus/securedrop,chadmiller/securedrop,jeann2013/securedrop,chadmiller/securedrop,jaseg/securedrop,GabeIsman/securedrop,jeann2013/securedrop,heartsucker/securedrop,jaseg/securedrop,micahflee/securedrop,jrosco/securedrop,jeann2013/securedrop,kelcecil/securedrop,conorsch/securedrop,ageis/securedrop,conorsch/securedrop,jrosco/securedrop,harlo/securedrop,ageis/securedrop,harlo/securedrop,ageis/securedrop,jrosco/securedrop,jaseg/securedrop,jrosco/securedrop,jaseg/securedrop,pwplus/securedrop,GabeIsman/securedrop,micahflee/securedrop,GabeIsman/securedrop,garrettr/securedrop,kelcecil/securedrop,jaseg/securedrop,kelcecil/securedrop,harlo/securedrop,conorsch/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,micahflee/securedrop,pwplus/securedrop,ehartsuyker/securedrop,pwplus/securedrop,jaseg/securedrop,conorsch/securedrop,micahflee/securedrop,jeann2013/securedrop,kelcecil/securedrop,ehartsuyker/securedrop,garrettr/securedrop,pwplus/securedrop,ehartsuyker/securedrop,harlo/securedrop,ehartsuyker/securedrop,jrosco/securedrop,harlo/securedrop