Always remap old hosts to target host when encountered. When custom
vagrant server is defined, warn when tokens may be attached and allow
time for user to cancel.
Fixes#9442
This adds a prompt for a token description, which is now supported in
Vagrant Cloud. Pressing enter on the prompt uses the default description
of `"Vagrant login"`.
$ vagrant login
In a moment we will ask for your username and password to HashiCorp's
Vagrant Cloud. After authenticating, we will store an access token locally on
disk. Your login details will be transmitted over a secure connection, and
are never stored on disk locally.
If you do not have an Vagrant Cloud account, sign up at
https://www.vagrantcloud.com
Vagrant Cloud Username: justincampbell
Password (will be hidden):
Token description (Defaults to "Vagrant login"):
You are now logged in.
$
Which created a token with the default description of "Vagrant login":

Entering a description:
Token description (Defaults to "Vagrant login"): Justin's MacBook Pro

This fixes GH-6395 by only appending the access_token once. It also fixes a
bug that was never reported. If a user supplied an access_token for a box URL,
Vagrant would silently overwrite it.
After this commit, Vagrant only appends an access_token to the URL if no
value exists at the key.