internal: add Salesforce to list of broken auth providers

Fix #163

Change-Id: Id2c5f34b9d5b6854d59dd8122fb3460d83352b5c
Reviewed-on: https://go-review.googlesource.com/16856
Reviewed-by: Christian Ohler <ohler@driveshift.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

internal/token.go

@@ -101,11 +101,13 @@ var brokenAuthHeaderProviders = []string{
  "https://app.box.com/",
  "https://connect.stripe.com/",
  "https://login.microsoftonline.com/",
+ "https://login.salesforce.com/",
  "https://oauth.sandbox.trainingpeaks.com/",
  "https://oauth.trainingpeaks.com/",
  "https://oauth.vk.com/",
  "https://slack.com/",
  "https://test-sandbox.auth.corp.google.com",
+ "https://test.salesforce.com/",
  "https://user.gini.net/",
  "https://www.douban.com/",
  "https://www.googleapis.com/",