To correctly fix it, we need to create a JWS function

use of key thumbprints

* Use more specific test module (we'll create new test modules for future tools)
* Create gitlab-ci job for Debian Jessie and Debian Jessie + backports

Apply Nonce update to acme_account_delete script too

Closes #4

See merge request !7

Nonce: use Nonce received in latest ACME server response if available

Closes #4

See merge request !6

Use of ACME Directory and automatic update agreement to terms of service

* Update main script to:
  * Use the ACME directory to retrieve correct URLs from the ACME servers
  * Be able to update account informations (contact information and agreed terms of service)
  * Read terms of service links from either the ACME directory or account informations
  * Automatically update terms of service agreement with latest changes (user have to stay informed about the updates himself)
  * Fix HTTP errors handling
* Update configuration to:
  *  Configure ACME directory instead of CAUrl
  *  Allow to specify contact informations (email and phone number ; beware that Let's Encrypt servers don't allow phones)
* Update tests to:
  * Correctly setup before running tests without using global variable
  * Correctly clean setup after running tests (correctly remove ACME account and close temporary files)
  * Update requirements to latest dnspython release (as release 1.15 has fixed the dns updates issue)
* Update account delete script (you can find it in /tests/) according to updates of the main script

See merge request !5

Latest release of dnspython have fixed the bug from 1.14.0 release.

Note: as boulder doesn't currently support phone informations, we can't test it.

Clean log of useless headers
For base64, remove only trailing '=' as defined in acme drafts

As this variable is used with _send_signed_request we have
to be sure to not overwrite it in the script.

Set try count to begin with 1 and do 10 tries.

Enable ACMEDirectory for new-reg part.

Enable use of dynamic terms-of-service url for the agreement part too ( fixes #1 ).

Enable a way to add contact information inside account registration (email and phone).
It allows the ACME server provider to contact you on terms of service modifications.

Fix HTTPError exception handling (use correct error from urllib.error instead of IOError).