ein:url normalization issue (fails the passworded server test).
"No servers running here" warning is unsettling for I think the
majority of users who do not run jupyter locally.
Merge the login and open commands (open aliased to login). Add login
tests described in #352.
Attempt to improve user experience by synchronously executing
`ein:jupyter-server-start`. `ein:dev-prefer-deferred` custom variable
allows easy switch to compare sychronous versus old asynchronous behavior.
```
"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.
Use deferred and callbacks instead of `:sync t` for tkf requests which
is known to have issues. Query server attributes once on
notebooklist-open to avoid sequencing issue #176 (but allow Resync).
Under curl backend, a second request for the same "key" as a pending
request will abort the latter, which has resulted in a clobbered
curl-cookie-jar file, so merely warn and don't abort.
Fix#176
