Normalize url-or-port

```
"http://localhost:8888"
"http://localhost:8888/"
"http://127.0.0.1:8888"
"http://127.0.0.1:8888/"
"8888"
8888
```

Ideally these should converge to the same thing.  Since many hash
tables are keyed off `url-or-port`, forgetting to
normalize `url-or-port` with `ein:url` leads to missed cache hits and
general malaise.  So we try to do that.

Address a FIXME: apply callbacks to `ein:notebook-list-login-and-open`.

Removed py3.5 from travis build matrix to reduce developer strain.

features/step-definitions/ein-steps.el

@@ -39,6 +39,26 @@
                                     (ein:$notebook-notebook-name notebook))))
               (switch-to-buffer buf-name)
               (Then "I should be in buffer \"%s\"" buf-name))))))
+(When "^I login if necessary"
+      (lambda ()
+        (multiple-value-bind (url-or-port token) (ein:jupyter-server-conn-info)
+          (when token
+            (When "I call \"ein:notebooklist-login\"")
+            (And "I wait for the smoke to clear")))))
+
+(When "^I wait for the smoke to clear"
+      (lambda ()
+        (ein:testing-flush-queries)))
+
+(When "^I enter the prevailing port"
+      (lambda ()
+        (multiple-value-bind (url-or-port token) (ein:jupyter-server-conn-info)
+          (let ((parsed-url (url-generic-parse-url url-or-port)))
+            (When "I type \"%d\"") (url-port parsed-url)))))
+
+(When "^I wait for the smoke to clear"
+      (lambda ()
+        (ein:testing-flush-queries)))
 
 (When "^I open notebooklist"
       (lambda ()

lisp/ein-jupyter.el

@@ -23,9 +23,6 @@
 
 ;;; Code:
 
-(require 'ein-core)
-(require 'ein-notebooklist)
-
 (defcustom ein:jupyter-server-buffer-name "*ein:jupyter-server*"
   "The name of the buffer to run a jupyter notebook server
   session in."

lisp/ein-notebooklist.el

@@ -32,6 +32,11 @@
 
 (require 'ein-core)
 (require 'ein-notebook)
+
+;; needs to be after ein-notebook else deferred in server-start breaks down
+;; has something to do with provide/require in contents-api
+(require 'ein-jupyter)
+
 (require 'ein-connect)
 (require 'ein-file)
 (require 'ein-contents-api)
@@ -190,10 +195,15 @@ To suppress popup, you can pass `ignore' as CALLBACK."
                                      (ein:$notebooklist-url-or-port it)
                                    (ein:default-url-or-port)))))
          (url-or-port
+          (if noninteractive
+              ;; noninteractive for testing only
+              (multiple-value-bind (url-or-port token) (ein:jupyter-server-conn-info)
+                (let ((parsed-url (url-generic-parse-url url-or-port)))
+                  (format "%d" (url-port parsed-url))))
             (completing-read (format "URL or port number (default %s): " default)
                              url-or-port-list
                              nil nil nil nil
-                           default)))
+                             default))))
     (ein:url url-or-port)))
 
 (defcustom ein:populate-hierarchy-on-notebooklist-open nil
@@ -901,7 +911,11 @@ FIMXE: document how to use `ein:notebooklist-find-file-callback'
 (defun ein:notebooklist-login (url-or-port password callback &optional retry-p)
   "Login to URL-OR-PORT with PASSWORD with notebooklist-open CALLBACK of arity 0."
   (interactive (list (ein:notebooklist-ask-url-or-port)
-                     (read-passwd "Password: ")
+                     (if noninteractive
+                         ;; noninteractive for testing only
+                         (multiple-value-bind (url-or-port token)
+                             (ein:jupyter-server-conn-info) token)
+                         (read-passwd "Password: "))
                      nil))
   (if password
       (ein:query-singleton-ajax