0.9.110: Fix error printing when login command fails (#32)

Currently, when the login command fails, it looks like this -

```
> github nelson nelson.example.com
/ Post https://nelson.example.com/auth/github: dial tcp 10.10.10.10:443: connect: operation timed oSuccessfully logged in to nelson.example.com
```

This is confusing as the login actually failed yet it says "Successfully logged in", and it also truncates the error message.

This PR fixes that by ensuring all the errors are printed properly without the spinner interfering. It also honours the global timeout setting, and moves the error to the end of the return arg list as per Go convention.

There is a minor change in timeout behaviour too - previously, the login command would wait until the server times out. Now, it has a default timeout of 60 seconds, in line with all the other commands.

0.9.107

Write errors to stderr (#31)

0.9.104: Implement `nelson stacks list -u` (#30)

* Implement `nelson stacks list -u`

The arg for this was implemented but wasn't actually plumbed through to the API call.

This PR plumbs it through, and also tidies a few minor things up. I've tested it against a Nelson cluster.

* build query string using url.Values instead

0.9.100

Master only

0.9.93

Generated tag from TravisCI for build 93

0.9.90

Generated tag from TravisCI for build 90

0.9.87

Generated tag from TravisCI for build 87

0.9.84

Generated tag from TravisCI for build 84

0.9.81

Generated tag from TravisCI for build 81

0.9.78

Generated tag from TravisCI for build 78