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).

This part use ACMEDirectory in requests to ACME server.
Next part will remove last remaining CAUrl code and enable dynamic agreement url.

This commit update configuration constraints to use ACMEDirectory instead of CAUrl.
Next part will use effectively this new configuration to do requests to ACME server.

openssl tests:
we don't manage the OpenSSL code, so these tests are useless.

exsitence domain tests:
commented as dynamic DNS updates can create new domains.

configuration tests:
configuration management has a lot changed, so we'll have to
make new tests.

Remove the code managing FUSE and use configuration files instead.

Finally, ask ACME server to delete account key as it is only temporary files
and we don't save them.