Returns user info for the ECMWF WebAPI
wf_user_info(user)
user (email address) used to sign up for the ECMWF data service,
used to retrieve the token set by wf_set_key
returns a data frame with user info
if (FALSE) { # \dontrun{
# set key
wf_set_key(user = "test@mail.com", key = "123")
# get user info
wf_user_info("test@mail.com")
} # }