Added provider for CloudSigma cloud.

Added provider for CloudSigma cloud.

Provider for CloudSigma (https://www.cloudsigma.com) uses CloudSigma API v2.0
(https://cloudsigma-docs.readthedocs.org/en/2.10/).

Minimal client for communicating with the CloudSigma Web API from Go program was implemented as
separate library github.com/Altoros/gosigma. This library is published under AGPLv3 license.

gosigma library is added as dependency to dependencies.tsv file.

https://code.launchpad.net/~maxim-perenesenko/juju-core/cloudsigma/+merge/221540

(do not edit description out of merge proposal)

[maximp, 2014-05-30 13:21:32]

Please take a look.

[fwereade, 2014-06-02 10:47:55]

I made a *very* few first-pass comments, but it's really going to be hard to
review all this in one go. Would you please break it up a little? I'd recommend
starting with the config type first and leaving the Environ implementation out
for a while...

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
File provider/cloudsigma/config.go (right):

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
provider/cloudsigma/config.go:63: "storage-auth-key",
I'm pretty sure region should be immutable.

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
provider/cloudsigma/config.go:125: // to ensure the object we return icfgs
internally consistent.
s/icfgs/is/

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
File provider/cloudsigma/config_test.go (right):

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
provider/cloudsigma/config_test.go:62: var newConfigTests = []struct {
Ideally, put these definitions inside the test method. We've found there's a
distressing tendency for people to abuse them when they're global :(.

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
provider/cloudsigma/config_test.go:71: err:    ".* must not be empty.*",
Please don't use .* in tests except when you *really* have to. It masks all
kinds of embarrassments ;).

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
provider/cloudsigma/config_test.go:159: info:   "can change region",
I don't think this is meaningful.

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
provider/cloudsigma/config_test.go:237: fail := failReader{fmt.Errorf("error")}
This sort of test makes me happy, thank you.

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
provider/cloudsigma/config_test.go:286: err:    ".* must not be empty.*",
as above, please avoid unless *really* necessary

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/confi...
provider/cloudsigma/config_test.go:319: c.Errorf("secrect field %s not found in
configFields", field)
s/secrect/secret/

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/const...
File provider/cloudsigma/constraints_test.go (right):

https://codereview.appspot.com/101970045/diff/20001/provider/cloudsigma/const...
provider/cloudsigma/constraints_test.go:94: c.Logf("test (%d): %+v", i, t)
It's generally more convenient to log all the tests as they go past... and it's
nice to get the test description *before* the failure.

[maximp, 2014-06-09 11:44:29]

Please take a look.