fix wget progress bar in non-tty (Vagrant)
fix wget progress bar in non-tty (Vagrant)

add comment to explain why we're not using PhantomJS from the repos.

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