Generates user tokens for individual users.
Returns a new user token for this user.
User Token must be kept secret and transferred only over SSL, as it's effectively as good as a user's email and password.
The following are the examples of HTTP status codes including errors that API can generate
|Response codes||Response content||Description|
|200 OK||e111f69d-9dd0-89c7-a8b3-86200f9421f3||Everything worked correctly. A token has been retrieved.|
|404 Not Found||Object not found||An user not found.|